ANSWERS No 1 - 20

1.Anatomy and histology of normal skin. The epidermis. Epidermal cells

The skin is one of the largest organs in the body, having a surface area of 1.8 m2 and making up about 16% of body weight.Skin is composed of three layers: the epidermis, the dermis and the hypodermis.The dermis is attached to an underlying hypodermis, also called subcutaneous connective tissue, which stores adipose tissue.

Epidermis has 5 layers -

Stratum germinativum,

Stratum spinosum

Stratum granulosum

Stratum lucidum

Stratum corneum

Component of the dermis-

   Papillary dermis

   Reticular dermis

Skin appendages -

Hair follicals,sweat glands (merocrine,apocrine),sebaceous gland .

Epidermis

The epidermis is denned as a stratified squamous epithelium which is about 0.1 mm thick, although the thickness is greater (0.8-1.4 mm) on the palm and sole. Its prime function is to act as a protective barrier.

The main cell of the epidermis is the keratinocyte, which produces the protein keratin  The four layers of the epidermis  represent the stages of maturation of keratin by keratinocytes.

Stratum germinativum

(Stratum basale)

The basal cell layer of the epidermis, the deepest layer, rests on a basement membrane, which attaches it to the dermis. It consists mostly of keratinocytes which are either dividing or nondividing. The cells contain keratin tonofibrils and are secured to the basement membrane by hemidesmosomes. Melanocytes make up 5-10% of the basal cell population. These cells synthesize melanin and transfer it via dendritic processes to neighbouring keratinocytes.

     Melanocytes are most numerous on the face and other exposed sites and are of neural crest origin.

Merkel cells are also found, albeit infrequently, in the basal cell layer.

These cells are closely associated with terminal filaments of cutaneous nerves

and seem to have a role in sensation. Their cytoplasm contains neuropeptide

granules, as well as neurofilaments and keratin.

Vitamin A plays an important role in the development of keratinocytes

Stratum spinosum

The cells that are divided in the statum germinativum soon begin to accumulate many desmosomes on their outer surface which provide the characteristic prickles” (seen on the close-up view) of the stratum spinosum (SS), which is often called the prickle-cell layer.

Stratum granulosum

The cells of the stratum granulosum (SGR) accumulate dense basophilic keratohyalin granules. These granules contain lipids, which along with the

desmosomal connections, help to form a waterproof barrier that functions to prevent fluid loss from the body.

Stratum lucidium

Stratum Lucidium lies on the lower portion of the stratum corneum and consists of a thin clear strip of glistening, translucent, flattened cells without granules or nuclei. Stratum lucidum is present only in the skin of palms and soles. All mitoses are confined to what is termed the malpighian layer (germinative zone ), which consists of both the stratum basale and the stratum spinosum. The stratum corneum, the stratum lucidum, and the stratum granulosum are collectively referred to as the zone of keratinization, or as the cornified zone.

Stratum corneum

The most superficial layer of the epidermis is called the stratum corneum.

This layer is acellular. It is made up of flattened scale like elements (squames)

containing keratin filaments embedded in protein. The squames are held together by a glue like material containins lipids and carbohydrates. The presence of lipid makes this layer highly resistant to permeation by water. The thickness of the stratum corneum is greatest where the skin is exposed to maximal friction e.g., on the palms and soles.

Epidermal cells

Epidermal cells are

composed of:

- keratinocytes (make up

about 85% of cells) ;

- melanocytes;

- mast;

- langerhans cells,

- cells of Merkel, and

undefined cells.

Melanocytes

Melanocytes are dendritic cells derived from the neural crest and lying on the basement membrane. Melanocytes produce the pigment melanin in elongated, membrane-bound organelles known as melanosomes from phenylalanine via tyrosine by series of reactions catalyzed initially by tyrosinase giving the skin its color. Pigmentation is related more to melanin synthesis than to the number of skin melanocytes.

Langerhans cells

Langerhans cells have immunological functions, which can provide traps for contact antigens and present them to Tcells.

Functions of keratinocytes

Synthesis of the fibrillar proteins gives the stratum corneum its toughness.

Secretion of a large number of cytokines, which have an important effect on lymphocyte and granulocyte function. Synthesis of a wide range of growth factors which play an important role in wound healing. The factors controlling synthesis and secretion of these factors may be important in the pathogenesis of skin diseases.

2.Anatomy and histology of normal skin. The dermis. Components of the dermis.  Fibers, cells, ground substance.

Anatomy and histology-

The skin is one of the largest organs in the body, having a surface area of 1.8 m2 and making up about 16% of body weight.Skin is composed of three layers: the epidermis, the dermis and the hypodermis.The dermis is attached to an underlying hypodermis, also called subcutaneous connective tissue, which stores adipose tissue.

Epidermis has 5 layers -

Stratum germinativum,

Stratum spinosum

Stratum granulosum

Stratum lucidum

Stratum corneum

Component of the dermis-

   Papillary dermis-

   Reticular dermis

Skin appendages.

Hair follicals,sweat glands (merocrine,apocrine),sebaceous gland,nail.

Papillary dermis

The papillary dermis (PD) contains vascular networks that have two important functions. The first being to support the avascular epidermis with vital nutrients and secondly to provide a network for thermoregulation. The vasculature is organized so that by increasing or decreasing blood flow, heat can either be conserved or dissipated. The vasculature interdigitates in areas called dermal papillae (DP). The papillary dermis also contains the free sensory nerve endings and structures called Meissner’s corpuscles in highly sensitive areas.

Reticular dermis

The reticular layer of the dermis (RD) consists of dense irregular connective tissue, which differs from the papillary layer (PD), which is made up of mainly loose connective tissue (note the difference in the number of cells). The reticular layer of the dermis is important in giving the skin it overall strength and elasticity, as well as housing other important epithelial derived structures such as glands and hair follicles.

Components of the dermis

The dermis is composed of:

- Collagen fibers: The dermis is composed mainly of collagen fibers, which are synthesized by fibroblast. The thickness of collagen depends on different factors such as age, sex and body sites. The collagen layer is organized into a smooth superficial layer under the epidermis at the level of papillae and is coarse in the deeper layers. The collage fibers give the skin its toughness and elasticity.

- Elastic fibers: are associated with the collagen fibers and both are surrounded by mucopolysaccharides.

- Reticular fibers.

- Cells.

- Ground Substance: The base of the dermis is a supporting matrix or ground substance which is composed of polysaccharides and protein which are linked to produce macromolecules with a remarkable capacity for holding water in their domain. Within and associated with this matrix are two kinds of protein fibers: collagen, which has a great tensile strength and forms the major constituent of the dermis, and elastin, which forms only a small proportion of the bulk.

- The dermis contains the specialized sensory organs and the skin

appendages. Below the dermis there is a fatty layer known as the subcutaneous

tissue.

Dermal cells

The cells of the dermis are derived from the reticulum cell, the primitive mesenchymal cell. The cells of the dermis include :

Fibroblasts: form the fibrous tissue and the matrix

(ground substance).

Functions of fibroblasts:

1. Production of collagen and elastic tissue.

2. Synthesize of mucopolysaccharides .

3. Metabolize cholesterol and steroids.

Histiocytes are parts of the reticulo-endothelial system. Histiocytes are large phagocytic cells either fixed to the interstitial tissues or wandering .

3.Anatomy and histology of normal skin. Vasculature and innervation. The appendages of the skin (hairs, nails, glands).

Anatomy and histology of skin- he skin is one of the largest organs in the body, having a surface area of 1.8 m2 and making up about 16% of body weight.Skin is composed of three layers: the epidermis, the dermis and the hypodermis.The dermis is attached to an underlying hypodermis, also called subcutaneous connective tissue, which stores adipose tissue.

Epidermis has 5 layers -

Stratum germinativum,

Stratum spinosum

Stratum granulosum

Stratum lucidum

Stratum corneum

Component of the dermis-

   Papillary dermis-

   Reticular dermis

Nerve Supply of the Skin

The skin is richly supplied with sensory nerves. Dense networks of nerve fibres are seen in the superficial parts of the dermis. In contrast to blood vessels some nerve fibres do penetrate into the deeper parts of the epidermis.

       Apart from sensory nerves the skin receives autonomic nerves which supply smooth muscle in the walls of blood vessels; the arrectores pilorum muscles; and myoepithelial

cells present in relation to sweat glands. They also provide a secretomotor supply to sweat glands. In some regions (nipple, scrotum) nerve fibresinnervate smooth muscle present in the dermis.

Blood Supply of the Skin

Blood vessels to the skin are derived from a number of arterial plexuses. The deepest plexus is present over the deep fascia. There is another plexus just below the dermis (rete cutaneum or reticular plexus); and a third plexus just below the level of the dermal papillae (rete subpapillare, or papillary plexus). Capillary loops arising from this plexus pass into each dermal papilla. Blood vessels do not penetrate into the epidermis. The epidermis derives nutrition entirely by diffusion from capillaries in the dermal papillae. Veins from the dermal papillae drain through plexuses present in the dermis into a venous plexus lying on deep fascia.

A special feature of the blood supply of the skin is the presence of numerous arterio-venous anastomoses that regulate blood flow through the capillary bed and thus help in maintaining body temperature.

Appendages of skin-

Hair-Hairs are found over the entire surface of the skin, with the exception of the glabrous skin of the palms, soles, glans penis and vulval introitus. The density of follicles is greatest on the face. Embryologically, the hair follicle has an input from the epidermis, which is responsible for the matrix cells and the hair shaft, and the dermis, which .contributes the papilla, with its blood vessels, and nerves. There are three types of hair:

l  Lanugo hairs are fine and long, and are formed in the fetus at 20 weeks gestation. They are normally shed before birth, but may be seen in premature babies.

l   Vellus hairs are the short, fine, light coloured hairs that cover most body surfaces. «

l  Terminal hairs are longer, thicker and darker and are found on the scalp, eyebrows, eyelashes, and also on the pubic, axillary and beard areas. They originate as vellus hair; differentiation is stimulated at puberty by androgens.

Structure of Hair

• Hair papillae is the lower end of the hair. It appears as a bulbous swelling known as the hair bulb.

• Hair root is the intrafollicular portion of the hair known as the hair matrix or the hair root. Keratinocytes form the hair matrix.

• Hair shaft is made up of keratinized cells. It is composed of the hair cuticle or sheath, the cortex beneath it and the medulla in the center. The hair cuticle is the outer layer. The inner root sheath is made up of the cuticle, Huxley and Henle layer. The outer root sheath extends from the epidermis to the  hair bulb.

Sweat gland- sweat glands are tube-like and coiled glands, located within the dermis, which produce a watery secretion. There are two separate types: eccrine and apocrine.

 Eccrine :Eccrine sweat glands develop from down budding of the epidermis. The secretory portion is a coiled structure in the deep reticular dermis.Their number and size varies in the skin over different parts of the body. They are most numerous in the palms and soles, the forehead and scalp, and the axillae.
 Apocrine :Also derived from the epidermis, apocrine sweat glands open into hair follicles and are larger than eccrine glands. Apocrine sweat glands are confined to some parts of the body including the axilla, the areola and nipple, the perianal region, the glans penis, and some parts of the female external genitalia.

Nail-The nail is a phylogenetic remnant of the mammalian claw and consists of a plate of hardened and densely packed keratin. It protects the finger tip and facilitates grasping and tactile sensitivity in the finger pulp.

The nails are convex, translucent horny plates that are composed of:

• The body - the exposed part of the nail.

• The free edge - the anterior extension from the body.

• Nail root - the portion of the nail extending under the skin.

• Nail lanula - the whitish crescent near the base of the nail.

• Nail bed - part of the epidermis on which the nail lies.

• Nail matrix - the part of the nail below the nail root.

• Nail folds - the folds that bound the nail posteriorly and laterally.

• Eponychium - the crescent shaped thin membrane that stretches

Sebaseous gland-Sebaceous glands are found associated with hair follicles ,especially those of the scalp, face, chest and back, and are not found on nonhairy skin. They are formed from epidermisderived cells and produce an oily sebum, the function of which is uncertain.

4.Anatomy and histology of normal skin. The function of the skin. Histopathology (acanthosis, acantholysis, dyskeratosis, parakeratosis, hyperkeratosis)

Functions of the skin-

Regulates body temperature.

Prevents loss of essential body fluids, and penetration of toxic substances.

Protection of the body from harmful effects of the sun and radiation.

Excretes toxic substances with sweat.

Mechanical support.

Immunological function mediated by Langerhans cells.

Sensory organ for touch, heat, cold, socio-sexual and emotional sensations.

Vitamin D synthesis from its precursors under the effect of sunlight and introversion of steroids.

Acanthosis-

Acanthosis describes thickening of the epidermis. It is classified into

flat (the entire site thickens moderately; e.g., in chronic eczema),

proriasiform (epidermal protrusions are extended)

papillomatous (the epidermis projects upwards; e.g., with viral warts or seborrheic keratosis),

and pseudocarcinomatous (pseudosquamous cell carcinomas project irregularly downward; e.g., chronic ulcer margin, deep mycoses

Acantholysis- it is the dispersion of keratinocytes resulting from the dissociation of keratinocyte intercellular adhesion, particularly that of desmosomes. Intercellular spaces and blisters form, with acantholytic cells (spherical keratinocytes that have lost their intercellular adhesion) floating inside. Acantholytic cells have a tendency to become dyskeratotic . The phenomenon is found in pemphigus, Hailey-Hailey disease and Darier’s disease, and it may also be found in part of the lesions of actinic keratosis, keratoacanthoma, warty dyskeratoma and squamous cell carcinoma.

Dyskeratosis- occurs when some keratinocytes keratinize abnormally before they reach the horny cell layer. The keratinocytes become apoptotic and necrotic. The nuclei shrink and contain eosinophilic cytoplasm. Since intercellular bridges between the peripheral keratinocytes are lost, the cells become round. Dyskeratosis is often found with inflammatory diseases and malignant tumors.

Parakeratosis is caused by incomplete keratinization in which nuclei remain in the cells of the horny cell layer. In normal skin, keratinocytes denucleate when they reach the horny cell layer; however, keratinocyte formation in inflammatory diseases such as psoriasis vulgaris or in tumorous diseases such as actinic keratosis and Bowen’s disease takes place so quickly that most of the nuclei remain in the horny cell layer. It is frequently accompanied by hyperkeratosis and hypogranulosis. The nuclei remain physiologically in the mucous membranes.

Hyperkeratosis-The horny cell layer becomes abnormally thick. This is seen in psoriasis vulgaris, ichthyosis and callus. In ichthyosis, hyperkeratosis is due to detachment and exfoliation of the horny cell layer, a process called retention hyperkeratosis. Keratinization associated with hair follicles is called follicular keratosis.

5.Principles of local therapy in dermatology. Physiotherapy.

Topical therapy

Topical treatment has the advantage of direct delivery and reduced systemic

toxicity. It consists of a vehicle or base which often contains an active ingredient.

Vehicles are defined as follows:

 Lotion.

 Cream.

 Gel.

 Ointment.

 Paste.

Lotion

A liquid vehicle, often aqueous or alcohol-based, which may contain a salt in solution. A shake lotion contains an insoluble powder (e.g. calamine lotion).

Cream

A semi-solid emulsion of oil-inwater; contains an emulsifier for stability, and a preservative to prevent overgrowth of microorganisms.

Gel

A transparent semi-solid, nongreasy emulsion.

Ointment

A semi-solid grease or oil, containing little or no water but sometimes with added

powder. No preservative is usually needed. The active ingredient is suspended

rather than dissolved.

Paste

An ointment base with a high proportion of powder (starch or zinc oxide) producing a stiff consistency.

Choice of Vehicle

Lotions evaporate and cool the skin and are useful for inflamed/exudative conditions, e.g. for wet wraps. The high water content of a cream means

that it mostly evaporates; it is also non-greasy and easy to apply or remove.

Ointments are best for dry skin conditions such as eczema. They rehydrate and occlude, but (being greasy) are difficult to wash off and are less acceptable to patients than creams.

Pastes are ideal for applying to well defined surfaces, such as psoriatic plaques, but  are also hard to remove.

Gel same as for lotion

 

Physiotherapy of skin-

 Preservation, enhancement, or restoration of movement and physical function • Impaired or threatened by disability, injury, or disease • That utilizes therapeutic exercise, physical modalities, assistive devices, and patient education. • Has a very important role in encouraging patient to remain positive and in control of their condition.

Phototherapy:

l  Ultraviolet (UV) light is classified into three wavelength ranges. From longest to shortest, they are UVA (320 nm to 400 nm), UVB (290 nm to 320 nm) and UVC (200 nm to 290 nm). The shorter is the wavelength, the lower is the penetration and the greater is the energy of the light. Applied for cutaneous tumor ,vitiligo vulgaris ,mycosis fungoides,psoriasis vulgaris,scleroderma.

l  The patient is subjected to infrared (IR) radiation at a wavelength of 760 nm or longer so as to raise the temperature, improve blood circulation, and achieve anti-inflammatory action.

Radiotherapy:

l  Electron beams These are beta rays. They are used for treating lymphomas and keloids.

l  Soft X-rays are low-voltage, low-energy X-rays (about 20 kV).used for treating carcinoma ,malignant lymphoma.

Thermotherapy:

l  a lesion is warmed to 42 ℃ to 47 ℃ with warm water, a body warmer, a medical exothermic sheet.

This is effective in treating sporotrichosis, chromomycosis and infections of atypical mycobacteria. It may be performed as a treatment for malignant skin tumors in conjunction with chemotherapy or irradiation therapy.

Hyperbaric oxygen (HBO) therapy:

l   increase oxygen dissolved in the blood and to increase the partial pressure of oxygen in the tissues.used in gas gangrene.

6.Principles of systemic therapy in dermatology.

Treatment that reaches cells throughout the body by travelling through blood stream.

When to consider systemic therapy in dermatology?

l  When topical drug does not reach the target tissue.eg-onycomycosis

l  When the disease has the systemic sequences and systemic treatment needed . Eg-lupus erythematous .bacterial skin in patient with valvular disease.

l  When topical therapy ineffective and systemic therapy is more effective, eg-severe psoriasis,severe eczema,severe blistering disease.

l  When the cutaneous disease is extensive making topical therapy inconvenient (systemic therapy is not more toxic than local)eg-extensive fungal infection.

  

7.Types of lesions. Primary skin lesions (vesicle, bulla, pustules, macule).

Two types of lesions, primary and secondary lesions.

Primary:An eruption that occurs in normal skin without any preexisting eruptions is called a primary lesion.

Vesicle-

A vesicle is a small blister (less than 5 mm in diameter) consisting of clear fluid accumulated within or below the epidermis. Vesicles may be grouped as in dermatitis herpetiformis (subepidermal).

Bulla-

A bulla is similar to a vesicle but larger: greater than 5 mm in diameter. The blisters of bullous pemphigoid and pemphigus vulgaris.

Pistules-

A pustule is a visible collection of free pus in a blister. Pustules may indicate infection (e.g. a furuncle), but not always, as pustules seen in psoriasis, for example, are not infected.

Macules-

A macule is a localized area of colour or textural change in the skin. Macules can be hypopigmented, as in vitiligo; pigmented, as in a freckle; or erythematous as in a capillary haemangioma.

             

layer	Lesion stages	Examples
epidermis	Macula=>disappear or stay for life time Vesicle => serous fluid=>erosion =>crust Bulla =>serous fluid=> 1)  erosion=> crust                    2)  =>crust Pustula=>1) erosion=>crust         2) crust=>macula=>disappear    Papula=>1) disappear         2) macula=> disappear	Vitiligo,tatoo, Eczema,herpes zoster virus Epidermolysis Folliculitiss, acne Warts,psoriasis
Dermis Papillary	Macula=>1)disappear         2)sec macula =>disappear or hyperpigmented         3)for all life ( non inflammatory) Pustula=>ulcer=>crust=>scar Papula=>1)sec macule=>disappear         2)disappear Wheal=>1)macula=>disappear        2)disappear	Telengiectasia Tatoo,vein nevus,ecchymosis Secondary syphilis Urticaria ,lichen planus
Dermis Reticular	Pustula=>ulcer=>crust=>scar Tubucle=>1)ulcer=>crust=>scar          2)scar	Acne,fungus infection TB of skin,syphilis,leprosis
Subcutaneous	Pustula=>ulcer=>crust=>scar Nodule=> non inflammatory 1)scar                  Inflammatory 2)ulcer=>crust=>scar	Furuncle,carbuncle Small lipomas,Syphilis T.B of skin, leposy, 3rd syphillis

               


8.Types of lesions. Primary skin lesions (papule, nodule or tubercle, tumor, wheal)

Two types of lesions,primary lesions and secondary lesions.

Primary skin lesions:An eruption that occurs in normal skin without any preexisting eruptions is called a primary lesion.

Papule-A papule is a small solid elevation of the skin, generally denned as less than 5 mm in diameter. Papules may be flattopped, as in lichen planus; domeshaped, as in xanthomas; or spicular if related to hair follicles.

Nodule-

Similar to a papule but larger (i.e. greater than 5 mm in diameter), nodules can involve any layer of the skin and can be oedematous or solid. Examples include a dermatofibroma and secondary deposits. Also in leprosy, T.B of skin and syphilis

Tumor-An intensely proliferative nodule with an elevation of 30 mm or more in diameter is called a tumor.

Wheal-A wheal is a transitory, compressible papule or plaque of dermal oedema, red or white in colour and usually signifying urticaria.

9.Types of lesions. Secondary skin lesions (secondary macule, scales, crusts, erosion, ulcer).

 Two types of lesions are there. Primary lesions and secondary lesions.

Secondary lesions:is an eruption that occurs secondarily after a primary or other skin lesion.

Secondary macules-When the macule occurs due to excessive formation of

melanin or some other black pigment, it is called a hyperpigmented macule.

When the skin in the region of the macule is white due to complete loss of melanin, it is called a depigmented macule.When the loss of melanin is

only partial, the macule is called hypopigmented . Seen in telangiectasia and ecchymosis.

  

Scales-

A scale is an accumulation of thickened, horny layer keratin in the form of readily detached fragments. Scales usually indicate inflammatory change and thickening of the epidermis. They may be fine, as in 'pityriasis'; white and silvery, as in psoriasis; or large and fish-like, as seen in ichthyosis.

Scales are observed when multiple horny cell layers pathologically exfoliate in diseases such as psoriasis.

Crusts-

Crust is solidified keratin and exudate that forms on an erosion or on ulcerous skin (eg-in psoriasis vulgaris and herpes simplex). A crust of clotted blood is called a bloody crust (commonly called a scab)

Erosion-

often develops after breakage of a blister or pustule. It appears red and is infiltrated with serous fluid in most cases. It frequently forms in the lips and oral mucosa, from their lack of keratinocytes.

Healing is without scarring. It frequently occurs in diseases that cause intraepidermal blistering, such as impetigo contagiosa, pemphigus, epidermolysis bullosa and herpes simplex, and in diseases that cause subepidermal blistering, such as pemphigoid, burns and spontaneous intensely itchy eruptions (e.g., Duhring dermatitis herpetiformis, atopic dermatitis).

Ulcer-

An ulcer is the complete deficiency of tissue at sites deeper than erosion, reaching from the dermis to subcutaneous tissues. In healing, an ulcer is repaired by granular tissue and scarring is left. The bottom of an ulcer often has bleeding, serous exudation, and a crust that includes part of the previous lesion. Ulceration occurs secondarily in many cases after blood circulation disorder (e.g., stasis dermatitis, collagen disease, vasculitis, blocked arteries, diabetes), infection and malignant tumor.

10.Types of lesions. Secondary skin lesions (excoriation, lichenification, vegetation).

Two types of lesions, primary and secondary lesions.

Secondary lesions:is an eruption that occurs secondarily after a primary or other skin lesion.

Excoriation-

Excoriation is partial damage to the epidermis by injury or rubbing. The symptoms vary by the depth of excoriation. When it occurs within the horny cell layer, it heals by scaling. When it occurs in a deeper site, blood or other fluids may be exuded. In both cases, healing is without scarring.

Lichenification-

Lichenification is the thickening and hardening of skin that results from chronic disease. The sulci cutis and cristae cutis are clearly observed . Lichenification is found in chronic eczema, lichen simplex chronicus and atopic dermatitis.

Vegetation-

growth of pathologic tissue consisting of multiple closely set papillary masses.

  

   11. Pyodermas. Etiology. Superficial folliculitis. Furuncle. Carbuncle. Sycosis barbae

Pyodermas

Pyoderma means any skin disease that is pyogenic (has pus). These include superficial bacterial infections such as impetigo, impetigo contagiosa, ecthyma, folliculitis, Bockhart's impetigo, furuncle, carbuncle, tropical ulcer, etc 

Etiology

Caused by bacterias such as                   

Orgnism	Infection
Commensa	Erythrasma, pitted keratolysis trichomycosis axilaris
Staphylococcal	Impetigo, ecthyma, folliculitis, secondary infection
Streptococcal	Erysipelas, cellulitis, impetigo, ecthma, necrotizing fasciitis
Gram-negative	Secondary infection, folliculitis,cellutis
Mycobacterial	TB(lupus vulgaris, warty tuberculosis, scrofuloderma), fish tank granuloma, Buruli ulcer, leprosy
Spirochaetal	Syphilis (e.g primry, secondary), lyme disease (erythema chronicum migrans)
Neisseria	Gonorrhoea (pustules], meningococcaemia (purpura)
Others	Anthrax (pustule), erysipeloid (pustule)

Superficial folliculitis

Definition:

 is an acute pustular infection of multiple hair follicles

Cause:

 Staph. aureus isusually but not invariably responsible

 The most common causes of follicle damage are:

Friction from shaving or tight clothing

Heat and sweat, such as that caused by wearing rubber gloves or waders

Certain skin conditions, such as dermatitis and acne

Injuries to your skin, such as from scrapes or surgical wounds

Coverings on your skin, such as plastic dressings or adhesive tape

Pathogenesis:

A hair follicle is infected by Staphylococcus aureus or Staphylococcus

epidermidis. A minor trauma, obstruction and scratch

around a hair follicle, or topical application of steroids may

induce the infection. The hair follicle becomes inflamed.

Clinical features:

Clusters of small red bumps or white-headed pimples that develop around hair follicles

Pus-filled blisters that break open and crust over

Red and inflamed skin

Itchy or burning skin

Tenderness or pain

A large swollen bump or mass

Diagnostic:

Your doctor is likely to diagnose folliculitis by looking at your skin and reviewing your clinical history. If the usual treatments don't clear up your infection, he or she may use a swab to take a sample of your infected skin. This is sent to a laboratory to help determine what's causing the infection. Rarely, a skin biopsy may be done to rule out other conditions.

Treatment:

Acute staphylococcal infections are treated with antibiotics

both systemic (e.g. flucloxacillin or erythromycin) and topical (e.g. fusidic acid,

mupirocin or neomycin). Chronic and recurrent cases are more difficult. Carrier

sites, e.g. the nose, need treatment with a topical antibiotic (e.g. mupirocin). General

measures such as improved hygiene, regular bathing or showering, the use of

antiseptics in the bath and on the skin (e.g. chlorhexidine) can help, but courses of

oral antibiotics may be needed

Furuncle (Boil)

Definition:

Are pus-filled lesions that are painful and usually firm. Boils occur when infection around the hair follicles spreads deeper, and are usually located in the waist area, groin, buttocks, and under the arm. In other words it is a deeper form of folliculitis 

Etiology:

Infection - Staphylococcus aeurus, injury, or irritation

Clinical features:

Pus in the center of the boil

Whitish, bloody discharge from the boil

Diagnostic:

A thorough medical history and physical examination. After examining the lesions, culture the wounds (take a sample of the drainage of the wound, allow it to grow in the laboratory, and identify specific bacteria) to help verify the diagnosis and to help in selecting the best treatment.

Treatment:

A warm compress may be used to help promote drainage of the lesion

Surgical incision (making an opening in the skin overlying the infection) and drainage of the pus

Oral or intravenous (IV) antibiotics (to treat the infection)

Cultures may be obtained to identify the bacteria causing the infection 

Keeping the skin clean helps to prevent these conditions from occurring and is essential for healing. Scrub your hands with soap and warm water for at least 20 to 30 seconds after touching a boil and do not re-use or share washcloths or towels. Change the dressings often and place the dressings in a bag that can be tightly closed and thrown out.

Carbuncle

Definition:

Carbuncles are clusters of boils that are usually found on the back of the neck or thig

Etiology:

Staphylococcus aureus is the most common bacteria

Clinical features:

 Pus in the center of the boils

Whitish, bloody discharge from the boils

Fever

Fatigue

Tenderness and pain at the site

Diagnostic:

Same as furuncle

Treatment:

Same as furuncle 

Sycosis barba

Definition:

This is an inflammation caused by ingrowing hairs. It mainly affects black men who shave and is most noticeable on the face and neck. People who get bikini waxes may develop barber's itch in the groin area. This condition may leave dark raised scars (keloids).

Etiology:

Staph. aureus

Clinical features:

Papules, pustules surrounded by erythema in the beard region mostly occurring in males after puberty

Diagnostic:

Swab is done, taken to the lab for further investigation

Treatment:

Antibiotic creams like  mupirocin (Bactroban)

Antibiotics both systemic (e.g. flucloxacillin or erythromycin) and topical (e.g. fusidic acid,

mupirocin or neomycin).

Light therapy with a medicated cream

Laser hair removal 

12. Scabies: etiology, ways of transmission, ways of transmission, diagnostic, differential diagnosis, treatment.

Definition:

It’s an intensely pruritic, highly contagious infestation of the skin caused by a parasite

Etiology:

Sarcoptes scabiei  

Ways of transmission:

Skin to skin contact, sex partners, children playing, infected bed linens because the mite can survive away from the body for 2-5 days

Diagnostic:

Direct visualization of the mite, egg or feces.

Mineral oil should be placed on the end of a burrow, preferably where a black dot is visible

The should then be scraped with a number 5 scapula and put on a slide

Differential diagnosis:

Insect bite

Pyoderma

Papular urticarial

Atopic dermatitis

Contact dermatitis

Treatment:

Topical agents:

• Permethrin 5% cream: single application, kept for 12 hours. Repeat application in a week may be  advised. Permethrin may be used in young children.

• Gamma benzene hydrochloride (GBHC, Lindane) 1% cream orlotion. GBHC is used as a single application on dry skin kept for 12 to 24 hours. A repeat application after 7 days is often recommended.        Not recommend for application in infants.

• Benzyl benzoate 25% emulsion: applied for three consecutive days.

• 6 to 10% sulphur ointment : applied for 3 to 5 consecutive day, application is messy.

• Crotamiton lotion or cream: less effective, may have a non-specific anti-pruritic effect.

• Monosulfirum-impregnated soaps are sometimes advised as aprophylactic in outbreaks.

Systemic therapy:

• Ivermectin, a macrolide without antibacterial activity has both ecto- and endo- parasitic activities.

• A single dose of ivermectin 200 microgram per kg of body weight is an effective drug particularly in crusted scabies.

• It is not recommended in children younger than 5 years old

Adjunct therapy:

• Antibacterials for pyoderma and topical steroid for Eczematization.

• Antihistamines for pruritus.

• Intralesional steroids may be needed for the treatment of nodular scabies.

13. Scabies: clinical features, atypical forms, diagnostic, treatment. Pediculosis: clinical forms, treatment.

Clinical features:

• The scalp, face and the palms and soles are usually spared sites in the usual cases.

• The lesions are readily infected with bacteria and impetigo, folliculitis, oozing and crusting are commonly observed as localized or extensive infective eczema

• Diagrams showing sites of predilection for scabies infestation on (a) the front of the trunk and limbs, and (b) the back of the trunk and limbs

 Atypical forms:

• Scabies in infants and in elderly people: infantile scabies shows involvement of palms and soles as well as the face and scalp. In elderly people, the trunk may be more severely infested.

• Scabies incognito: inadvertent application of topical steroid may modify the clinical picture of

scabies.

• Scabies in very clean individuals may show few lesions, thus confusion may arise as to the true

nature of the itch.

Diagnostic:

Direct visualization of the mite, egg or feces.

Mineral oil should be placed on the end of a burrow, preferably where a black dot is visible

The should then be scraped with a number 5 scapula and put on a slide

Treatment:

Topical agents:

• Permethrin 5% cream: single application, kept for 12 hours. Repeat application in a week may be advised. Permethrin may be used in young children.

• Gamma benzene hydrochloride (GBHC, Lindane) 1% cream or lotion. GBHC is used as a single application on dry skin kept for 12 to 24 hours. A repeat application after 7 days is often recommended. Not recommend for application in infants.

• Benzyl benzoate 25% emulsion: applied for three consecutive days.

• 6 to 10% sulphur ointment : applied for 3 to 5 consecutive day,application is messy.

• Crotamiton lotion or cream: less effective, may have a non-specific anti-pruritic effect.

• Monosulfirum-impregnated soaps are sometimes advised as a prophylactic in outbreaks.

Systemic therapy:

• Ivermectin, a macrolide without antibacterial activity has both ecto- and endo- parasitic activities.

• A single dose of ivermectin 200 microgram per kg of body weight is an effective drug particularly in crusted scabies.

• It is not recommended in children younger than 5 years old

Adjunct therapy:

• Antibacterials for pyoderma and topical steroid for Eczematization.

• Antihistamines for pruritus.

• Intralesional steroids may be needed for the treatment of nodular scabies.

Pediculosis:

Definition:

 • Infestation with lice became less common in the postwar years, but the incidence has recently

increased.

• There are three areas of the body usually affected by two species of wingless insects- Pediculus humanus, infecting the head and body (Pediculosis capitis, Pediculosis corporis), and Phthirus pubis, the pubic louse.

• each female lays 60–80 encapsulated eggs attached to hairs-“nits”;

• head lice are transmitted via combs, brushes, and hats, being more common in girls than boys. The infestation is heaviest behind the ears and over the occiput;

• the main feature of all lice infestations is severe itching, followed by scratching and secondary infection.

Clinical forms and Treatments:

Head lice

Cause

Head lice are still common, affecting up to 10% of

children even in the smartest schools.

The head louse itself measures some 3–4 mm in length and

is greyish, and often rather hard to find.

However, its egg cases (nits) can be seen easily enough,

firmly stuck to the hair shafts.

Spread from person to person is achieved by head-to-head

contact, and perhaps by shared combs or hats.

Presentation and course

The main symptom is itching, at first around the sides and

back of the scalp and then all over it.

Scratching and secondary infection soon follow and, in

heavy infestations, the hair becomes matted and smelly.

Draining lymph nodes are often enlarged

Complications

Secondary bacterial infection may be severe enough to

make the child listless and feverish.

Differential diagnosis

All patients with recurrent impetigo or crusted eczema on

their scalps should be carefully examined for the presence of

nits.

Investigations

None are usually required.

Treatment

Malathion, carbaryl and permethrin preparations are probably the treatments

of choice now. They kill lice and eggs effectively; malathion has the extra value

of sticking to the hair and so protecting against reinfection for 6 weeks. The

policy whereby public health authorities rotate their use, with the aim of

lessening the risk of resistant strains emerging, has fallen out of favour now.

Lotions should remain on the scalp for at least 12 h, and are more effective than

shampoos. The application should be repeated after 1 week so that any lice that

survive the first application and hatch out in that interval can be killed. Other

members of the family and school mates should be checked. A toothcomb helps

to remove nits but occasionally matting is so severe that the hair has to be

clipped short. A systemic antibiotic may be needed to deal with severe

secondary infection. Some recommend, as an alternative to the treatments

mentioned above, that the hair should be combed repeatedly and meticulously

with a special detection comb’abut the efficacy of this method has still to be

established. However, a head louse repellent, containing 2% piperonal, is

available over the counter and may be worth a trial for those who are repeatedly

reinfested. Systemic ivermectin therapy is reserved for infestations resisting the

treatments listed above.

Body lice

Cause

Body lice infestations are now uncommon except in the

unhygienic and socially deprived.

Morphologically the body lice look just like the head lice,

but lay their eggs in the seams of clothing in contact with the

skin.

Transmission is via infested bedding or clothing

Presentation and course

Self-neglect is usually obvious; against this background

there is severe and widespread itching, especially on the

trunk.

The bites themselves are soon obscured by excoriations

and crusts of dried blood or serum.

In chronic untreated cases (‘vagabond’s disease’) the skin

becomes generally thickened, eczematized and pigmented;

lymphadenopathy is common.

Differential diagnosis

In scabies, characteristic burrows are seen. Other causes of

chronic itchy erythroderma include eczema and

lymphomas, but these are ruled out by the finding of lice

and nits.

Investigations

Clothing should be examined for the presence of eggs in the

inner seams.

Treatment

First and foremost treat the infested clothing and

bedding.

Lice and their eggs can be killed by high temperature

laundering, by dry cleaning and by tumbledrying.

Less competent patients will need help here. Once this

has been achieved, 5% permethrin cream rinse or 1%

lindane lotion (USA only) may be used on the patient’s skin.

Pubic lice

Cause

Pubic lice (crabs) are broader than scalp and body lice,

and their second and third pairs of legs are well adapted to

cling on to hair.

They are usually spread by sexual contact, and most

commonly infest young adults.

Presentation

Severe itching in the pubic area is followed by

eczematization and secondary infection.

Among the excoriations will be seen small blue-grey

macules of altered blood at the site of bites.

The shiny translucent nits are less obvious than those of

head lice.

Pubic lice spread most extensively in hairy males and

may even affect the eyelashes.

Differential diagnosis

Eczema of the pubic area gives similar symptoms

but lice and nits are not seen.

Investigations

The possibility of coexisting sexually transmitted

diseases should be kept in mind.

Treatment

Carbaryl, permethrin and malathion are all effective

treatments.

Aqueous solutions are less irritant than alcoholic ones. They

should be applied for 12 h or overnight to all parts of the trunk,

including the perianal area and to the limbs, and not just to the

pubic area.

Treatment should be repeated after 1 week, and infected

sexual partners should also be treated. Shaving the area is not

necessary. Infestation of the eyelashes is particularly hard to

treat, as this area is so sensitive that the mechanical removal of

lice and eggs can be painful.

Applying a thick layer of petrolatum twice a day for 2 weeks

has been recommended. Aqueous malathion is effective for

eyelash infestations but does not have a product licence for this

purpose. 

14. Acne. Etiopathogenesis, clinical forms, clinical features, diagnostic, treatment.

Acne:

Acne is a skin condition that occurs when your hair follicles become plugged with oil and dead skin cells. Acne usually appears on your face, neck, chest, back and shoulders. Effective treatments are available, but acne can be persistent. The pimples and bumps heal slowly, and when one begins to go away, others seem to crop up.

 Acne is most common among teenagers, with a reported prevalence of 70 to 87 percent. Increasingly, younger children are getting acne as well.

Depending on its severity, acne can cause emotional distress and scar the skin. The earlier you start treatment, the lower your risk of lasting physical and emotional damage.

Etiopathogenesis:

Four main factors cause acne:

• Oil production
• Dead skin cells
• Clogged pores
• Bacteria

It’s caused by hyperkeatosis (thickening of stratum corneum and over production of keratin) which causes blocking of sebaceous gland excretion in the hair follicules

Clinical forms:

Whiteheads (closed plugged pores)

Blackheads (open plugged pores — the oil turns brown when it is exposed to air)

Small red, tender bumps (papules)

Pimples (pustules), which are papules with pus at their tips

Large, solid, painful lumps beneath the surface of the skin (nodules)

Painful, pus-filled lumps beneath the surface of the skin (cystic lesions)

• Acne excoriee: due to squeezing, affects depressed or obsessional young women.

    • Chloracne: caused by certain aromatic halogenated industrial chemicals.

•  Conglobate: a mass of burrowing abscesses and sinuses with scarring.

   • Cosmetic: pomade and cosmeticinduced comedonal/papular acne (mainly seen in the USA).

   • Drug-induced: by systemic steroids, androgens and topical steroids.

   • Infantile: mostly found on the faces of male infants. Cause: unknown.

   • Physical: occlusion by the back of a wheel-chair or on a violinist's chin.

Clinical feature:

Hyperproduction of sebum

Hyperkeratosis

Hyperplasia

Inflammation by Priopionibacterium acnes

Diagnostic:

Direct visualization, medical history (drugs like oral contraceptive)

TREATMENT

The psychological impact of acne (perceived cosmetic disfigurement) should be assessed individually in each patient and therapy modified accordingly.

Mild Acne

 Topical antibiotics (clindamycin and erythromycin)

Benzoyl peroxide gels (2 %, 5 %, or 10 %)

Topical retinoids (tretinoin)

Moderate Acne Oral tetracyclines added to the preceding regimen

Severe Acne Isotretinoin (has severe adverse effects)

15. Seborrhea. Etiopathogenesis, clinical features, diagnostic, treatment.

Seborrheic dermatitis (SD) is a very common chronic dermatosis characterized by redness and scaling occurring in regions where the sebaceous glands are most active, such as the face and scalp, and in the body folds. Mild scalp SD causes flaking, i.e., dandruff.

 Synonyms: “Cradle cap” (infants), eczematoid seborrhea, pityriasis sicca (dandruff).

ETIOPATHOGENESIS

Sebum production is normal, but the eruption often occurs in the sebaceous gland areas of the scalp, face and chest. Endogenous and genetic factors, and an overgrowth of the commensal yeast Pityrosporum ovale, are involved. The condition is severe in some patients with HIV infection.

CLINICAL FEATURES

There is some controversy as to whether seborrheic dermatitis in infants, adolescents and adults is the same disease, because there are minor differences in the clinical courses . Dermatitis appears as follicular eczema on seborrheic sites or intertriginous areas in the head, face, axillary fossa, neck and external genitals. The main features of the lesions are oleaginous scales and erythematous plaques that may be slightly itchy.

        In infants, yellowish crusts begin to form on the scalp, eyebrows and forehead. In infants, scaly erythematous plaques may also form 2 to 4 weeks after birth. In most cases they resolve 8 to 12 months after birth. In adolescents and adults, pityroid scales (commonly called dandruff) increase and scaly erythematous lesions form on the eyebrows and nasolabial groove. Seborrheic dermatitis is chronic and recurrent.

DIAGNOSIS

Usually made on clinical findings

TREATMENT

The scalp lesions require the use of a medicated shampoo (e.g. containing coal tar, selenium sulphide or ketoconazole), either alone or following the application of 2% sulphur and 2% salicylic acid cream left on for several hours. Facial, truncal and flexural involvement respond to an

imidazole or antimicrobial, often combined with 1% hydrocortisone, in a

cream or ointment base (e.g. Daktacort and Vioform-Hydrocortisone). Lithium succinate (Efalith) cream is also effective. Recurrence is common and repeated treatment often necessary

16.Herpes Simplex. Etiology, clinical features, diagnostic, treatment.

Two types of HSV are there.Nongenital herpes simplex-Incubation Period 2- to 20-day.infection is normally seen after sexual contact (with infected person) in young adults,

Neonatal herpes simplex-Neonates may be infected during delivery or in the perinatal period

ETIOLOGY-

Herpes simplex is a very common acute/ self-limiting vesicular eruption due to infection with Herpesvirus hominis.

CLINICAL FEATURE-

Neonatal HSV

Acute gingivostomatitis is a common presentation in those with symptoms. Vesicles on the lips.

mucous membranes quickly erode and are painful Sometimes the cornea is involved.

The illness is often accompanied by fever, malaise and local lymphadenopathy and lasts about 2 weeks.

Herpetic whitlow is another presentation .

A painful vesicle or pustule is found on a finger.

Nongenital HSV:

acute vulvovaginitis, penile or perianal lesions.

Rarely, herpes simplex may appear in a zosteriform dermatomal distribution. The outbreak of groups of vesicles is often preceded for a few hours, by tingling or burning.

Crusts form within 24-48 hours, and the infection fades after a week.

Attacks may be precipitated by respiratory infection,sunlight,locla trauma.

DIAGNOSIS-

Clinical suspicion confirmed by Tzanck smear, viral culture, or antigen detection

TREATMENT-

l  The treatment of choice for recurrent mild facial or genital herpes simplex is acyclovir (Zovirax) cream (applied 5 times a day for 5 days)

 (which reduces the length of the attack and the duration of viral shedding)

l  more severe episodes warrant oral treatment with acyclovir (200 mg 5 times a day for 5 days)

(which shortens the attack. Long-term oral administration is useful in those with frequent recurrent attacks. Intravenous aciclovir may be life-saving.)

l  in the immunosuppressed and in infants with eczema herpeticum. Genital herpes simplex can also be treated with oral famciclovir or valaciclovir. In those with genital herpes simplex.

17.Herpes Zoster. Etiology, clinical features, diagnostic, treatment

Herpes zoster is an acute, self-limiting, vesicular eruption occurring in a dermatomal distribution

ETIOLOGY-

it is caused by a recrudescence of Varicella zoster virus.

CLINICAL FEATURES-

Pain, tenderness or paraesthesia in the dermatome may precede the eruption by 3-5 days.

Erythema and grouped vesicles follow, scattered within the dermatomal area

The vesicles become pustular and then form crusts which separate in 2-3 weeks to leave scarring

Secondary bacterial infection may occur.

Herpes zoster is normally unilateral and may involve adjacent dermatomes.

The thoracic dermatomes are affected in 50% of cases and, in the elderly, involvement of the ophthalmic division of the trigeminal nerve is particularly common .

Patient may develop chickenpox.

Some scattering of vesicles or disseminated  haemorrhagic vesicles raise the possibility of immunosuppression or underlying malignancy.

Local lymphadenopathy is usual.

as is sensory disturbance ,including pain, numbness and paraesthesia.

DAIGNOSIS-

Visual examination

lgM antibody test

Polymerase chain reaction-with lymph collected from blisters

Viral culture- with samples of lesions

Tzanck smear -(but cant differentiate from HSV)

TREATMENT-

In mild case, treatment is symptomatic, with rest, analgesia and bland drying preparations such as calamine lotion.

Secondary bacterial infection may require a topical antiseptic or antibiotic.

More severe cases may be treated, if seen within 48 hours of onset, with oral aciclovir (800 mg 5 times per day for 7 days) or famciclovir (750 mg once daily for 7 days) .

immunosuppressed patients often require intravenous aciclovir.

Oral prednisolone, given early in the course of herpes zoster for 14 days.

18.Warts. Etiology, clinical features, diagnostic, treatment.

ETIOLOGY-

Warts (verrucae) are common and benign cutaneous tumours due to infection of epidermal cells with human papilloma virus.

CLINICAL FEATURES-

Ø  Common warts. dome-shaped papules or nodules with a papilliferous surface.

usually multiple, and are commonest on the hands or feet in children but also affect the face and genitalia.

  Their surface interrupts skin lines. Some facial warts are 'filiform' with     fine digit-like projections.

Ø  Plane warts. smooth flat-topped papules, often slightly brown in colour, and commonest on the face and dorsal aspects of the hands.

usually multiple and resist treatment.

Ø  Plantar warts. seen in children and adolescents on the soles of the feet; (pressure causes them to grow into the dermis)

 painful and covered by callus,dark punctate spots (thrombosed capillaries).

Ø  Mosaic warts are plaques on the soles.

Ø  Genital warts. In males these affect the penis, and in homosexuals, the perianal area. In females, the vulva, perineum and vagina may be involved .

DIAGNOSIS

Usually made on clinical findings

TREATMENT

In children, 30-50% of common warts disappear spontaneously within 6 months.

Hand and foot warts should be pared by a scalpel or using a pumice stone.

Topical: Salicylic and lactic acids(e.g. Duofilm. OcclusalSalactol. Salatac]

Glutaraldehyde (e.g. Glutarol)

Formaldehyde (3% aqueous)

Podophyllotoxin (0.15%) cream

Cryotherrapy :3-4 weeks

Others:

Intralesional bleomycin

Laser surgery

Interferon-beta or -gamma

19. Molluscum Contagiosum. Etiology, clinical features, diagnostic, treatment

Molluscum contagiosum are discrete pearly-pink umbilicated papules which are caused by a DNA pox virus. 

 Mollusca mainly affect children or young adults. Spread is by contact, including sexual transmission or on towels.

The virus enters through a break in the skin or a hair follicle, and proliferates in the suprabasal cell layer of the epidermis. When a wart is scratched, the contents adhere to the epidermis and cause autoinfection.

ETIOLOGY-

produced by molluscum contagiosum virus, a virus in DNA pox virusfamily.

CLINICAL FEATURES-

 The dome-shaped papule, a few mm in diameter, has a punctum and if squeezed, releases a cheesy material.

The lesions are usually multiple and grouped, and are commonest on the face, neck and trunk . Isolated ones may go unrecognized.

Multiple molluscum contagiosum may appear on the face of patients with AIDS.

mild itching may present.

The trunk and extremities of infants are most frequently affected.

When sexually transmitted, the genitalia, lower abdomen, and medial thighs are involved.

DIAGNOSIS-

Molluscum contagiosum is easily diagnosed by the clinical features.

In sudden occurrence of multiple molluscum contagiosum in adults, AIDS involvement is highly suspected.

TREATMENT-

removal is by expressing the contents with forceps, curettage under local anaesthesia or cryotherapy.

These measures are poorly tolerated in young children, and the best approach is to instruct the parents to squeeze out the 'ripe' lesions after the child has bathed.

  

 20.Fungal infections of the glabrous skin. Etiology (pathogens), clinical signs, diagnostic, local and systemic treatment.

glabrous (skin without hair) skin is usually infected by tinea  corporis.

Infected pet animals. The inflammation is transmitted from infected pets such as cats or dogs.

Auto inoculation from a primary fungal focuses elsewhere on the skin.

Direct infection from one patient to another.

Etiology-

Tinea corporis is occasionally caused by Microsporum canis, which parasitizes dogs and cats.

causative dermatophyte in most cases of tinea corporis is Trichophyton rubrum.

Clinical signs-

The most  common sites involved are the exposed areas such as face, neck and extremities especially in children, but any site of the body may be involved.

it appears as small erythematous papules on the trunk and extremities, gradually spreading centrifugally.

The papule tends to heal centrally, giving the lesion a ring shape.

Although the center of the lesion subsides with mildly abnormal pigmentation, the periphery is elevated, and papules, vesicles and scales form there.

Itching is present.

Diagnosis-

l    Examination of a skin scraping from the rash under a microscope using a special test

l    Skin biopsy

l    Culture of the skin for fungus

Treatment-

Topical anti fungal creams -that contain miconazole, clotrimazole, ketoconazole, terbenifine, or oxiconazole are often effective in controlling ringworm. Apply 2 time per day for 7 to 10 days.

Antifungal medication - itraconazole and terbinafine

Topical steroids and ointments.