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5 layers of epidermis
o basalis, spinosum, granulosum, lucidium + corneum
5 layer functions of epidermis
- basalis –skin regenerates
- spinosum –largest
- granulosum –has granules
- lucidium –very thick (prominent in palms + feet)
- corneum –gets dislocated
melanin formed by...
Melanin is formed within the melanosomes of the melanocytes by conversion of tyrosine to dopa through tyrosinase. Dopa is hydroxylated to melanin.
- In a langerhan
- rod-shaped and attached to a vesicle at one end giving a characteristic tennis racquet appearance
- ELASTIC fibers
- appendageal structures
4 skin adnexa
- Hair follicles
- Sebaceous glands
- Eccrine sweat glands
- Apocrine sweat glands
- elevated, solid area, up to 5mm
- flat, circumscribed area of any size distinguished from surrounding skin by discoloration.
- elevated, solid area, >5mm diameter.
- elevated, flat-topped area, usually >5mm diameter.
- fluid-filled raised area, up to 5 mm diameter.
- pus filled raised area
- rough and irregular
- due to chronic rubbing on skin
- treek bark
- Vesicle has eroded
- abnormal keratinization occurring prematurely in cells below stratum granulosum.
- malignancy? like keratoma
- loss of intercellular connections between keratinocytes
- start to break apart and separate
epidermal intercellular edema
diffuse epidermal hyperplasia
discontinuity of the skin with incomplete loss of the epidermis.
- discontinuity of the skin with complete loss of the epidermis and often of portion of the dermis and subcutis
- thickening of the stratum corneum by abnormal keratin
- retention of nuclei in stratum corneum
- linear pattern of melanocyte proliferation within the epidermal basal cell layer
- dark area on basal cell layer
- Mediated by local or systemic immunologic factors.
- Acute lesions: (days to weeks) inflammation (mononuclear cells), edema, epidermal and vascular injury.
- Chronic lesions: (months to years) significant alteration in epidermal growth (atrophy or hyperplasia), or dermal fibrosis.
Urticaria: Acute dermatosis
- Unknown cause in majority of cases.
- Pruritic edematous plaques and papules called wheals.
- Angioedema; closely related, deeper edema of dermis and subcutaneous fat.
- All ages, mostly 20-40 years old.
- Lesionsdevelop and fade within hours (<24 hrs). Episodes can last days or months.
- Develop on sites exposed to pressure such as trunk and distal extremities.
What is erthema multiforme assocatied with?
- 1. Infections: herpes simplex, mycoplasma, histoplasmosis, coccidiodomycosis, typhoid, leprosy.
- 2. Drugs: sulfonamides, penicillin, barbiturates, salicylates, hydantoins and antimalarials.
- 3. Malignant disease
- 4. Collagen vascular disease
- multiform lesions:macules, papules, vesicles and bullae
- TARGET LESION
- symmetrical on both extremities.
Steven Johnson Syndrome
- extensive febrile form of the disease--
- Hemorrhagic crusts involve the lips and oral mucosa
- might involve conjunctiva, urethra, genital and perianal areas.
- May result in life-threatening sepsis.
Toxic epidermal necrolysis
a severe variant , diffuse necrosis and sloughing of cutaneous and mucosal epithelial surfaces, producing a clinical picture analogous to extensive burn.