Integument 1 Lecture PDF

Integument Lecture (1) Integument • Composed of skin and skin appendages • Protects deeper tissues from injury, drying and invasion by foreign organisms • Play important roles in • Thermoregulation • Absorbs ultraviolet light • Metabolizes vitamin D • Limited role in excretion and absorption • Conta...

Integument Lecture (1) Integument • Composed of skin and skin appendages • Protects deeper tissues from injury, drying and invasion by foreign organisms • Play important roles in • Thermoregulation • Absorbs ultraviolet light • Metabolizes vitamin D • Limited role in excretion and absorption • Contains peripheral endings of sensory nerves • Q: Know the layers of epidermis Layers of Skin: Come Let’s Get Sun Burnt • Epidermis o Stratum Corneum o Stratum Lucidum o Stratum Granulosum o Stratum Spinosum o Stratum Basale • Dermis o Papillary dermis o Reticular dermis Biopsy: • If possible, biopsy a primary lesion • Biopsy characteristic areas in their diagnostic stage, NOT ruptured bullae, secondarily infected/scratched areas or involuting lesions • Try to include a margin with both lesion and surrounding normal skin • Captures histopathology only at one point in time in evolution of a lesion Shave Biopsy: • Removal of a "shave" superficial lesion tissue and/or to establish a diagnosis Punch Biopsy: • Removal of a "core" of tissue to establish a definitive diagnosis or to remove a small lesion Q: Which biopsy is used for a superficial lesion? - Shave Q: Which biopsy is used for a small lesions? - Punch Definitions: • Macule o Circumscribed flat colored area <1cm (<10mm) • Patch o Flat discoloration >1cm (>10mm) • Papule o Elevated, solid area <10mm • Plaque o Elevated, flat-topped area usually >10mm • Nodule o Solid, palpable, >10mm • Tumor o Solid, palpable >20mm • Cyst o Encapsulated cavity or sac lined by true epithelium o Squamous lined, filled w keratin • Blister: Vesicle or bullae o Vesicle § Fluid filled area <10mm o Bullae § Fluid filled area >10mm • Pustule o Intraepidermal/Subepidermal vesicle or bullae filled w pus • Erosion o Discontinuity of skin causing partial loss of epidermis • Ulceration o Discontinuity of skin causing complete loss of epidermis and possible loss of dermis • Fissure o Canyon-like crack through the epidermis and into the dermis o NO tissue lost • Excoriation o Deep, linear scratch o Often self induced • Wheals o Itchy, transient, elevated area w variable blanching and erythema due to dermal edema (erythema of the skin is due to dermal edema) • Scale o Dry, plate like excrescence usually due to excess stratum corneum • Crust o Hardened layer resulting from serum, blood, purulent exudate drying on skin surface • Purpura o Extravasation of RBCs into the skin or mucous membranes • Erythema o Redness of skin due to increased blood flow o NOT leakage of blood into the skin, may blanch • Telangiectasia o Visible persistent dilation of small, superficial cutaneous blood vessels o May blanch • Onycholysis o Separation of nail plate Histological Changes: • Hyperkeratosis o Thickened cornified layer o Prominent granular layer • Parakeratosis o Cells of cornified layer retain nuclei o Less prominent or absent granular layer (normal for mucous membranes) • Acanthosis o Thickened squamous epidermis o Rete ridges extend deep into dermis • Hypergranulosis o Hyperplasia of Stratum Granulosum o From intense rubbing • Spongiosis and Vesicles o Intraepidermal edema causes keratinocytes to splay apart in stratum spinosum o Vesicle formation due to sheared desmosomes • Acantholysis o Loss of desmosomes btwn keratinocytes o Cell shape changes from polygonal to round • Dyskeratosis o Premature keratinization of keratinocytes below granular layer o Bright eosinophilic cytoplasm