Common Dermatoses III and IV Flashcards Preview

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Flashcards in Common Dermatoses III and IV Deck (23)

Mechanism of lichen planus

Unknown antigen, but cell-mediated immunity (tons of T cells found in the skin lesion biopsies)


What is the lichenoid reaction pattern on pathology?

Huge infiltration of lymphocytes lined up at the dermal-epidermal junction


2 known possible causes of lichen planus

-Hep C (especially in oral lichen planus)


What are the 4 P's of lichen planus?

purple, papules, polygonal, pruritic


Most common sites for lichen planus

Wrist flexors (forearm surface), ankles, legs, genitalia


Lichen planus treatment

Self-limiting, usually goes away on its own in about 15 months
-topical steroids can be used if needed


What is tinea dermatophytosis?

(a) where does the infective organism live?
(b) how is it spread?

Tinea dermatophytosis = Ring worm

(a) Hangs in the stratum cornea => only in keratinized tissue (epidermis, hair, nails)
(b) Spread thru soil, animals, or other humans


Diagnostic tool for tinea dermatophytosis

See fungi w/ KOH prep

Septated, branching hyphae => tinea dermatophytosis (fungi causing ring worm)

Spaghetti and meatball' appearance of hyphae and spores = yeast malassezia furfur = causes tinea versicolor


Treatment for tinea dermatophytosis

(a) Response to steroids

Treat ring worm w/ topical or oral (second line) antifungals

(a) Gets worse when given steroids


How to differentiate dysplastic nevi and malignant melanoma on appearance

Often very hard! => need to do biopsy

Dysplastic nevi often don't fit the ABCDE pattern of benign lesions. Need to do skin exams very regularly (and w/ pictures) to see which lesions require biopsy


Why are dysplastic nevi dangerous?

6x higher risk of melanoma

-pts w/ sporadic dysplastic nevi + FHx of dysplastic nevi + FHx of melanoma = risk of melanoma approaches 100% by age 75


How to manage pts w/ dysplastic nevi

Very frequent skin checks, often use total body photographs to compare and note any changes

-biopsy the moles that you can't clinically distinguish from melanoma => get pathologic confirmation that not cancerous


What is a woods lamp?

Distinguish hypopigmentation and depigmentation


What two things do you want to ask a pt w/ psoriasis

-joint pain (psoriatic arthritis)
-counsel on CVD (psoriasis pts have increased risk for CVD)


What is dyshydrotic eczema?

Not sweating! Recurrent, bilateral, symmetrical vesicular eruptions on hands and feet

-vesicles classically on side of fingers w/ deep seeded 'tapioca pudding' sppearance
-really itchy


Differentiate dyshydrotic eczema from herpetic vesicles

Herpetic vesicles
-erythematous base
-very easily to pop

Dyshydrotic Eczema
-not on a red base
-are deeper rooted in the skin => don't burst very easily
-are itchy
-associated w/ topical exposures


How to treat dyshydrotic eczema

Assess for aggravating features: stress, topical exposure to soaps, detergents, irritating chemicals
-topical steroids



= Freckles!
On sun exposed areas of red and blond haired children
-keratinocytes contain more melanin, not more melanocytes


Differentiate ephelides and lentigines

(a) Mechanism
(b) Reaction to lack of sun exposure

Ephelides (freckles) and lentigines

(a) Ephelides = normal number of melanocytes with increased amount of melanin. While lentigines is a hyperplasia of the melanocytes in the epidermis
(b) Freckles go away during the winter (when not in the sun) while lentigines stay the same color regardless of sun exposure


Gender disparity in prognosis for melanoma

Males have lower survival rates at all ages


Most common location for melanomas in

(a) males
(b) females

Melanoma most common locations

(a) Males- trunk
(b) Females- legs


What causes actinic keratosis?

Chronic UVB sun exposure in elderly pts
-sun damaged skin


Why do you treat actinic keratosis?

Not just for cosmetic reasons, but also so they don't turn in squamous cell carcinoma