Dermatology Flashcards by Sammy Gilg

Epidermal layers

Californians Like Girls in String Bikinis - Corneum (keratin), Lucidum, Granulosum, Spinosum (desmosomes), Basale (stem cells)

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Epithelial cell junctions

From top to bottom: Tight junction (claudins and occludins), Adherens junction (CADherins - Ca dependent adhesions), Desmosome (keratin interactions), Gap junction (connexon channels), Hemidesmosomes (connects to basement membrane), Integrins (maintain INTEGRity of basolateral membrane)

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Albinism

NORMAL MELANOCYTE NUMBER - decreased melanin production due to decreased tyrosinase activity - FAILURE OF NEURAL CREST CELL MIGRATION

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Melasma

Hyperpigmentation during pregnancy

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Vitiligo

Complete depigmentation - autoimmune destruction of melanocytes

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Acne

Obstruction of pilosebaceous unit (can be caused by steroid use - androgen stimulation) - Tx: Isotretinoin

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Atopic dermatitis

TYPE I HYPERSENSITIVITY - common on skin flexures (antecubital fossa), starts on face in infancy (can be associated with asthma or allergic rhinitis)

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Allergic contact dermatitis

TYPE IV HYPERSENSITIVITY - linear/geometric shapes – Langerhans cells, CD4 T cells, SPONGIOTIC dermatitis

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Melanocytic nevus

Benign – intradermal (papular), junctional (flat macules)

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Psoriasis

Silvery scaling (knees and elbows), acanthosis with parakeratotis (nuclei still in stratum corneum), increased stratum spinosum and decreased granulosum, Auspitz sign (pinpoint bleeding when scales are scraped off) — Treatment can be topical (vitamin D analogs inhibit keratinocyte proliferation) or systemic (methotrexate)

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Rosacea

Face - erythematous papules and pustules - flushing in response to stimuli (alcohol, heat) - OLDER MEN - Tx: sunscreen, avoid triggers, metronidazole

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Seborrheic keratosis

FLAT, GREASY, STUCK ON - Kerain filled cysts (horn cysts) - Leser Trelat sign (sudden appearance of a bunch can mean GI or lymphoid malignancy)

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Verrucae

Warts - HPV 6/11 - epidermal hyperplasia, hyperkeratosis, koilocytosis

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Urticaria

Hives - pruritic wheals with mast cell degranulation - superficial dermal edema with lymphatic channel blockage - no epidermal changes

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Impetigo

S. aureus or S. pyogenes - honey colored crusts - Tx: mupirocin

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Cellulitis

PAINFUL, SPREADING - deeper dermis and subq infection - S. pyogenes or S. aureus

Erysipelas

Upper dermis and superficial lymphatics - S. pyogenes - well defined demarcation - Tx: Penicillin

Abscess

Almost always S. aureus - OFTEN MRSA!!

Necrotizing fasciitis

Anaerobic bacteria or S. pyogenes - CREPITUS (methane/CO2 production) - causes bullae and purple skin

Staph scalded skin syndrome

EXOTOXIN destroys keratinocyte attachment in strratum granulosum (SLOUGHING of skin, fever)

Herpes

HSV1 (mouth) and 2 (genitals) - Tx: thymidine kinase inhibitor

Molluscum contagiosum

Umbilicated papules (POXVIRUS) - children or sexually transmitted in adults (HIV patients)

Varicella zoster virus

Chickenpox (varicella - dew drop on rose petal) and shingles (zoster - dermatomal distribution) - Tx: thymidine kinase inhibitor

Hairy leukoplakia

White, painless plaques on tongue that can’t be scraped off - EBV - found in HIV patients

Pemphigus vulgaris

IgG aginst desmoglient (desmosomes) - flaccid intrapidermal bullae (acantholysis) --- oral mucosa also --- reticular (net like) immuno stain -- Nikolsky sign +

Bullous pemphigoid

IgG against hemidesmosomes ("down BULLO") -- tense blisters with eosinophils -- NO ORAL! -- linear pattern on immuno -- Nikolsky sign -

Dermatitis herpetiformis

Pruritic papules, vesicles, and bullae - IgA at dermal papillae - CELIAC!!!

Erythema Multiforme

Infections, drugs, cancers, autoimmune - TARGET LESIONS

Stevens-Johnson syndrome

Sulfas, cillins, seizure drugs, allopurinol --- fever, bullae, necrosis, sloughing of skin (2 mucous membranes involved) - TARGET LESIONS --- toxic epidermal necrolyisis is more severe (> 30% body area)

Acanthosis nigricans

Epidermal hyperplasia - hyperpigmented skin (axilla or neck) - velvety texture on skin, also commonly have skin tags -- hyperinsulinemia and visceral malignancy

Actinic keratosis

PREMALIGNANT d/t sun exposure --- rough, erythematous brownish papules -- risk of SCC - Tx: shave biopsy

Erythema nodosum

PAINFUL - subq fat on anterior shins - sarcoidosis, cocci, histo, TB, strep, leprosy, Crohns

Lichen Planus

6 Ps - Pruritic, Purple, Polygonal Planar Papules and Plaques --- Wickham striae on mucosa, sawtooth infiltrate of lymphocytes at dermal-epidermal junction --- HEPATITIS C

Pityriasis rosea

Herald patch --- CHRISTMAS TREE - self resolving in 6-8 weeks -- HHV 6 and 7 --- Tx: antihistamines and topical steroids

Sunburn

UVA (tanning and photoaging), UVB (sunburn)

Basal cell carcinoma

Pinky, pearly papule with telangiectasia, rolled borders, and central crust/ulcer --- MC skin cancer - sun exposed areas (UPPER LIP) -- nonhealing ulcers w/ infiltrating growth --- palisading nuclei

Squamous cell carcinoma

Second MC type - excessive exposure to sunlight, immunosuppression, arsenic exposure -- LOWER LIP/ear/hands -- can spread to lymph nodes -- ulcerative red lesions with scales (keratin pearls!)

Melanoma

S-100 tumor marker (neuroendocrine) -- Breslow depth is prognostic marker --- ABCDE -- superficial spreading, nodular, letigo, and sacral -- activating mutation in BRAF kinase (BRAF V600E - tx: vemurafenib)