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SKIN -PART-2

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CLASSIFICATION OF SKIN DISEASES Skin diseases are identified and classified

according to characteristic lesions (size, shape, color & location) and other signs and symptoms

Pruritis – itching

Edema – swelling

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ERYTHEMA – REDNESS

VESICLES – SMALL BLISTER-LIKE OR LARGER FLUID-FILLED

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PUSTULES –lesions contain pus

MACULAR – flat lesions

PAPULAR – raised lesions

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1.Disorders of Epidermal Maturation Ichthyosis.

2. Acute Inflammatory Dermatoses. Urticaria, Acute eczematous dermatitis, Erythema multiforme.

3. Chronic Inflammatory Dermatoses Psoriasis , Seborrheic dermatitis Lichen planus,

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4.Blistering (Bullous) Diseases. Pemphigus vulgaris, Bullous pemphigoid,, Dermatitis herpetiformis, NON INFLAMMATORY. Epidermolysis bullosa,and porphyria,

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5.Disorders of epidermal appendages Acne vulgaris, Rosasea ,

6.Panniculitis Erythema nodosum and erythema induratum,

7. Infections : Verrucae, Molluscum Contagiosun, Impetigo, Superficial Fungal Infections.

8. Metabolic disorders of skin.

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DISORDERS OF EPIDERMAL MATURATIONICHTHYOSIS

Most ichthyoses become apparent either at or around the time of birth.

Acquired (noninherited) variants also exist; in the acquired ichthyosis vulgaris in adults, there can be an association with lymphoid and visceral malignancies.

Primary categories include ichthyosis vulgaris (autosomal dominant or acquired), 

Congenital ichthyosiform erythroderma (autosomal recessive),

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URTICARIA (HIVES) Urticaria (hives) is a common disorder of

the skin characterized by localized mast cell degranulation and resultant dermal micro vascular hyper permeability.

This gives rise to pruritic oedematous plaques called wheals. 

Angioedema is closely related to urticaria and is characterized by deeper oedema of both the dermis and the subcutaneous fat.

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The Greek word eczema, meaning "to boil over," acute eczematous dermatitis. All forms of eczema are characterized by

red, papulovesicular, oozing, and crusted lesions that, if persistent, develop into raised, scaling plaques due to reactive acanthosis and hyperkeratosis

Based on initiating factors, eczematous dermatitis can be subdivided into the following categories: (1) allergic contact dermatitis, (2) atopic

dermatitis, (3) drug-related eczematous dermatitis, (4) photoeczematous dermatitis, and (5) primary irritant dermatitis

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 Eczematous dermatitis. 

A, Acute allergic contact dermatitis, with numerous vesicles on erythematous skin due to antigen exposure . 

B, Histologically, intercellular edema within the epidermis creates small, fluid-filled intraepidermal vesicles.

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Spongiosis characterizes acute eczematous dermatitis, hence the histologic synonym spongiotic dermatitis.

Unlike urticaria, in which edema is restricted to the superficial dermis, edema seeps into the intercellular spaces of the epidermis, splaying apart keratinocytes, particularly in the stratum spinosum.

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Erythema multiforme. A, The target-like clinical lesions consist of a central blister or zone of epidermal necrosis surrounded by macular erythema. B, Early lesions show lymphocytes collecting along the dermoepidermal junction where basal keratinocytes have begun to become vacuolated.

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Erythema multiforme is an uncommon, self-limited disorder that seems to be a hypersensitivity reaction to certain infections and drugs

(1) infections such as herpes simplex, mycoplasmal infections, histoplasmosis, coccidioidomycosis, typhoid, and leprosy, among others;

(2) administration of certain drugs (sulfonamides, penicillin, barbiturates, salicylates, hydantoins, and antimalarial);

(3) malignant disease (carcinomas and lymphomas); and

(4) collagen vascular diseases (lupus erythematosus, dermatomyositis, and polyarteritis nodosa

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An extensive and symptomatic febrile form of the disease, which is often but not exclusively seen in children, is called Stevens-Johnson syndrome. 

Typically, erosions and haemorrhagic crusts involve the lips and oral mucosa, although the conjunctiva, urethra, and genital and perianal areas may also be affected.

Secondary infection of involved areas due to loss of skin integrity may result in life-threatening sepsis.

Another variant, termed toxic epidermal necrolysis, results in diffuse necrosis and sloughing of cutaneous and mucosal epithelial surfaces, producing a clinical situation analogous to an extensive burn when both infection and fluid loss are clinical concerns

PSORIASIS Superficial idiopathic (unknown cause) skin disorder characterized by an abnormal rate of epidermal cell production and turnover

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Plaque psoriasis presented with characteristic pink lesions with silvery scales.

& Scalp psoriasis (mistaken for severe dandruff) redness on scalp,inflammation,thick scaling

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DEFINITION

Well defined

Erythematous

Silvery white scales

Typical Sites

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Koebner phenomenon

MORPHOLOGICAL TYPES

Psoriasis vulgaris

Guttate RupioidElephantinePustularOstraceous

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PALMO-PLANTAR PSORIASIS

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GUTTATE

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PUSTULAR PSORIASIS

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NAIL MANIFESTATIONS

Pits Onycholysis Thickening Oil drop sign Beau’s lines Sub.ung.Hyper.K

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Psoriasis is a common chronic inflammatory dermatosis affecting as many as 1% to 2% of people.

Persons of all ages may develop the disease. Psoriasis is sometimes associated with arthritis, myopathy, enteropathy, spondylitic joint disease, or the acquired immunodeficiency syndrome.

Psoriatic arthritis may be mild or may produce severe deformities resembling

the joint changes seen in rheumatoid arthritis

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Increased epidermal cell turnover results in

marked epidermal thickening (acanthosis), with regular downward elongation of the rete ridges sometimes described as appearing like test tubes in a rack

Mitotic figures are easily identified well above the basal cell layer, where mitotic activity is confined in normal skin.

 The stratum granulosum is thinned or absent, and extensive overlying parakeratotic scale is seen

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Seborrheic dermatitis is a chronic inflammatory dermatosis even more common than psoriasis, affecting 1% to 3% of the general population.

It classically involves regions with a high density of sebaceous glands, such as the scalp, forehead (especially the glabella), external auditory canal, retro auricular area, nasolabial folds, and the presternal area.

The individual lesions are macules and papules on an erythematous-yellow, often greasy base, typically in association with extensive scaling and crusting. Fissures may also be present,

particularly behind the ears

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Oily scalp, with scales that form from excess sebum

Can spread to face, ears & eyebrows

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LICHEN PLANUS.

Pruritic, purple, polygonal, planar papules, and plaques" are the tongue-twisting "six p's" of this disorder of skin and mucosa.

Lichen planus is usually self-limited and most commonly resolves spontaneously 1 to 2 years after onset, often leaving zones of post inflammatory hyperpigmentation.

Oral lesions may persist for years. Squamous cell carcinoma has been noted to occur in chronic mucosal and paramucosal lesions of lichen planus,

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Flat-topped pink-purple, polygonal papule has a white lacelike pattern that is referred to as

Wickham stria.

Biopsy specimen demonstrating a bandlike infiltrate of lymphocytes at the dermoepidermal junction, hyperkeratosis, hypergranulosis and pointed rete ridges (sawtoothing) as a result of chronic basal cell layer injury.

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 Lichen planus is characterized histologically by a dense, continuous infiltrate of lymphocytes along the dermoepidermal junction, a prototypic example of interface dermatitis .

Anucleate, necrotic basal cells may become incorporated into the inflamed papillary dermis, where they are referred to as colloid or Civatte bodies.

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Pemphigus is a blistering disorder caused by autoantibodies that result in the dissolution of intercellular attachments within the epidermis and mucosal epithelium.

The majority of individuals who develop pemphigus are in the fourth to sixth decades of life, and men and women are affected equally.

There are multiple variants: (1) pemphigus vulgaris, (2) pemphigus vegetans, (3) pemphigus foliaceus, (4) pemphigus erythematosus, and (5) paraneoplastic pemphigus

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Histologic levels of blister formation.  A, In a sub corneal blister the stratum

corneum forms the roof of the bulla (as in pemphigus foliaceus). 

B, In a suprabasal blister a portion of the epidermis, including the stratum corneum, forms the roof (as in pemphigus vulgaris).

 C, In a sub epidermal blister the entire epidermis separates from the dermis (as in bullous pemphigoid).

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Pemphigus vulgaris, by far the most common type (accounting for more than 80% of cases worldwide), involves the mucosa and skin, especially on the scalp, face, axilla, groin, trunk, and points of pressure.

oral ulcers that may persist for months before skin involvement appears. 

Pemphigus vegetans is a rare form that usually presents not with blisters but with large, moist, verrucous (wart-like), vegetating plaques studded with pustules on the groin, axillae, and flexural surfaces

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 A, Eroded plaques are formed on rupture of confluent, thin-roofed bullae, here affecting axillary skin.

 B, Suprabasal acantholysis results in an intraepidermal blister in which rounded (acantholytic) epidermal cells are identified (inset).

 C, Ulcerated blisters in the oral mucosa are also common as seen here on the mucosal portion of the lip.

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PEMPHIGUS FOLIACEUS. A, THE DELICATE, SUPERFICIAL (SUB CORNEAL) BLISTERS ARE MUCH LESS EROSIVE THAN SEEN IN PEMPHIGUS VULGARIS. 

B, SUB CORNEAL SEPARATION OF THE EPITHELIUM IS SEEN.

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Direct immunofluorescence of pemphigus.  A, In pemphigus vulgaris there is deposition of

immunoglobulin along the plasma membranes of epidermal keratinocytes in a reticular or fishnet-like pattern.

Also note the early suprabasal separation due to loss of cell-to-cell adhesion (acantholysis).

 B, In pemphigus foliaceus the immunoglobulin deposits are more superficial.

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Bullous pemphigoid.  A, Clinical bullae result from basal cell layer

vacuolization, producing tense, intact subepidermal blisters that are difficult to rupture given the roof formed by the full thickness of the epidermis. Ulceration results upon rupture as the blisters are sub epidermal.

 B, Histopathology shows an intact blister with eosinophils, as well as lymphocytes and occasional neutrophils, that may be intimately associated with basal cell layer destruction and the creation of the subepidermal cleft.

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Linear deposition of complement along the dermoepidermal junction in bullous pemphigoid; the pattern has been likened to ribbon candy. 

 

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Epidermolysis bullosa constitutes a group of disorders caused by inherited defects in structural proteins that lend mechanical stability to the skin.

The common feature is a proclivity to form blisters at sites of pressure, rubbing, or trauma, at or soon after birth.

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Epidermolysis bullosa.  A, Junctional epidermolysis bullosa showing

typical erosions in flexural creases.  B, A noninflammatory subepidermal blister

has formed at the level of the lamina lucida.

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Dermatitis herpetiformis is a rare disorder characterized by urticaria and grouped vesicles.

The disease affects predominantly males, often in the third and fourth decades. In some cases it occurs in association with intestinal celiac disease and responds to a gluten-free diet.

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 Dermatitis herpetiformis.  A, The blisters are associated with basal cell

layer injury initially caused by accumulation of neutrophils (microabscesses) at the tips of dermal papillae.

 B, Selective deposition of IgA autoantibody at the tips of dermal papillae is characteristic. 

C, Lesions consist of intact and eroded (usually scratched) erythematous blisters, often grouped (seen here on elbows and arms). 

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SEBACEOUS GLAND DISORDERS

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ACNE VULGARIS

Acne is a disorder of pilosebaceous follicles causing comedones,papules and pustules on the face ,chest and upper back

Affects many adolescents, about 80% between the ages of 12 – 15.

Result of hormonal changes that occur at puberty

SEBACEOUS GLANDS increase secretion of SEBUM, the oily fluid that is released through the hair follicles.

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Virtually universal in the middle to late teenage years, acne vulgaris affects both males and females, although males tend to have more severe disease.

Acne is seen in all races but is usually milder in people of Asian descent.

Acne vulgaris in adolescents is believed to occur as a result of physiologic hormonal variations and alterations in hair follicles, particularly the sebaceous gland.

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Acne is divided into noninflammatory and inflammatory types, although the types may coexist. The former consists of open and closed comedones. 

Open comedones are small follicular papules containing a central black keratin plug. This colour is the result of oxidation of melanin pigment (not dirt).

 Closed comedones are follicular papules without a visible central plug.

Inflammatory acne is characterized by erythematous papules, nodules, and pustules .

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A, INFLAMMATORY ACNE ASSOCIATED WITH ERYTHEMATOUS PAPULES AND PUSTULES. B, A HAIR SHAFT PIERCES THE FOLLICULAR EPITHELIUM, ELICITING INFLAMMATION AND FIBROSIS.  C, OPEN COMEDON

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TYPES OF ACNEMILD/ Comedonal

MODERATE/ Papulopustular

SEVER/ Nodulocystic

COMEDOCONAL ACNE:

Closed comedones (whiteheads) If duct blocked by dirt or dead cells, the sebum accumulates, causing a whitehead

Open comedones (blackheads)Sebaceous accumulation at the surface becomes oxidized and turns black, causing a blackhead

Non-inflammatory

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PAPULOPUSTULAR ACNE

Papules/Pustules

Once propionibacterium acnes (that’s always present on the skin)enters the broken skin, pus forms and a pimple or pustule results.

Squeezing the pimple spreads the infection

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NODULOCYSTIC ACNESoft nodules that are secondary comedones from repeated ruptures and reencapsulations

Painful and disfiguring.

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Rosacea is a common disease of middle age and beyond, affecting up to 3% . with a predilection for females. Four stages are recognized:

(1) flushing episodes (pre-rosacea), (2) persistent erythema and telangiectasia, (3) pustules and papules, and (4) rhinophyma-permanent thickening of the

nasal skin by confluent erythematous papules and follicular prominence.1

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Panniculitis is an inflammatory reaction in the subcutaneous adipose tissue that may preferentially affect (1) the connective tissue septa separating lobules of fat, or (2) the lobules of fat themselves.

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Verrucae are common lesions of children and adolescents, although they may be encountered at any age.

They are caused by human papillomaviruses. Transmission of disease usually involves direct contact between individuals or auto-inoculation.

Verrucae are generally self-limited, regressing spontaneously within 6 months to 2 years.

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Verruca vulgaris. 

A, Multiple papules with rough pebble-like surfaces. 

B (low power) and C, (high power) histology of the lesions showing papillomatous epidermal hyperplasia and cytopathic alterations that include nuclear pallor and prominent keratohyaline granules. 

D, In situ hybridization demonstrating viral DNA within epidermal cells.

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Molluscum contagiosum is a common, self-limited viral disease of the skin caused by a poxvirus.

The virus is characteristically brick shaped, has a dumbbell-shaped DNA core, and measures 300 nm in maximal dimension, and thus represents the largest pathogenic poxvirus in humans and one of the largest viruses in nature.

Infection is usually spread by direct contact, particularly among children and young adults

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BACTERIAL SKIN INFECTIONS

The most common bacterial skin infections are:

Impetigo FolliculitisCellulitis

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WHERE SCABIES IS MAINLY FOUND

In between the fingers Around the head and neck Groin areas

Itching a scabies rash can make the infection worse.

Scabies is passed from one person to another

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SYMPTOMS Scabies only affects the skin, outside the

body. Sever pruritus is the hallmark of scabies. extreme itching, which can worse at night

and after bathing

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FUNGAL SKIN INFECTIONS

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RINGWORM (TINEA) caused by many different fungi Symptoms Itchy, red, scaly patches which may look like a

ring because redder from outside and are normal inside

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CLASSIFICATION OF RINGWORM

Classified by its location on the body TINEA CORPORIS –Body ringworm On smooth areas, arms, legs, body

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TINEA PEDIS :”ATHLETES FOOT” on soles, between toes, toenail

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TINEA CAPITIS – “SCALP” ringworm. HIGHLY CONTAGIOUS

TINEA CRURIS – groin ringworm (jock itch)

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As opposed to deep fungal infections of the skin, where the dermis or sub cutis is primarily involved,

Superficial fungal infections of the skin are confined to the stratum corneum, and are caused primarily by dermatophytes.

These organisms grow in the soil and on animals and produce a number of diverse and characteristic clinical lesions

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Tinea capitis usually occurs in children and is only rarely seen in infants and adults.

Tinea barbae is a dermatophyte infection of the beard area that affects adult men; it is a relatively uncommon disorder. 

Tinea corporis, on the other hand, is a common superficial fungal infection of the body surface that affects persons of all ages, but particularly children.

 Tinea cruris occurs most frequently in the

inguinal areas of obese men during warm weather. Heat, friction, and maceration all predispose to its development.

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Tinea pedis (athlete's foot) affects 30% to 40% of the population at some time in their lives.

There is diffuse erythema and scaling, often initially localized to the web spaces.

Most of the inflammatory tissue reaction, however, has recently been shown to be the result of bacterial super infection and not directly related to the primary dermatophytosis.

Spread to or primary infection of the nails is referred to as onychomycosis.

 This produces discoloration, thickening, and deformity of the nail plate

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Tinea versicolor is caused by a yeast called Malassezia furfur

lives in the skin of most adults i.e. it is part of normal flora.

This exists in two forms, one of which causes visible spots.

Factors that can cause the fungus to become more visible include high humidity and immune or hormone abnormalities.

However, almost all people with this very common condition are perfectly healthy.

fungus is part of the normal adult skin, this condition is not contagious. It often recurs after treatment.

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There may be mild eczematous dermatitis associated with intraepidermal neutrophils .

Fungal cell walls, rich in mucopolysaccharides, stain bright pink to red with periodic acid-Schiff stain.

They are present in the anucleate cornified layer of lesional skin, hair, or nails

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