Derm E1: Intro

A lot of this is review from Patho

What are the layers of the epidermis? (sup → inf)

coreum, lucidum, granulosum, spinosum, basale

(come lets get sun burnt)

What are the layers of the dermis? (sup → inf)

papillary, reticular

What does the epidermis layer contain?

keratinocytes, melanocytes, Langerhans cells

What does the hypodermis layer contain?

adipose tissue, sensory neurons, blood vessels, hair follicles

What does the reticular layer of the dermis contain?

dense connective tissue and collagen fiber bundles

What do keratinocytes do?

produce keratin and lipids, form the epidermal water barrier, enable UVB absorption to activate vit D

What do melanocytes do?

produce pigment, stimulate melanin production to protect against UV radiation

What is the largest organ of the body?

skin

What is used to describe a person’s skin tone and the risk of burning or tanning in response to UV radiation?

Fitzpatrick Scale

What is a primary lesion?

beginning lesion of a skin disease

What is a macule?

non-palpable lesions that vary in pigmentation < 1cm

What is a patch?

non-palpable lesions that vary in pigmentation > 1cm

What are examples of macules/patches?

vitiligo, cafe-au-lait spots, mongolian spots, melanocytic nevus, freckles, petechiae

What are purpura?

red-purple lesions that do NOT blanch under pressure due to extravasation of blood from cutaneous vessels into the skin

What is a papule?

palpable discrete lesions < 0.5 cm

What is a plaque?

palpable, plateau-like discrete lesion > 0.5 cm

What is a nodule?

1-2 cm well-circumscribed solid or cystic lesion; can be superficial or deep

What is a tumor?

> 2cm solid or cystic lesion; can be superficial or deep

What is telangiectasia?

small, cherry red dilatations of the venules (spider vessels)

What disease is Telangiectasia commonly seen in?

rosacea

What are pustules?

small, circumscribed skin papule containing purulent material

What is special about follicular pustules?

usually contain a hair in the center; are conical or dome shaped

What are vesicles?

small < 5mm circumscribed papules containing clear, serous or hemorrhagic fluid; superficial, well-defined

What are bullae?

large > 5mm circumscribed vesciles

What are examples of dome-shaped vesicles?

contact dermatitis, dermatitis herpetiformis

What are examples of umbilicated vesicles?

herpes simplex

What are examples of flaccid vesicles?

pemphigus vulgaris

What are wheals?

irregularly shaped, elevated, edematous skin areas w/ well demarcated borders

What is excoriation?

superficial, often linear skin erosion caused by scratching

What is lichenification?

dry, leathery thickening of the epidermis w/ exaggerated/ increased skin markings; common in areas of folds

What is edema?

swelling due to accumulation of water in tissue

What are scales?

superficial epidermal cells that are dead and cast off from the skin

What is atrophy?

depression in the skin caused by the thinning of the epidermis or dermis

What does epidermal atrophy look like?

skin becomes transparent, loss of skin texture; cigarette paper like wrinkling, reveals the vessels below

What does dermal atrophy look like?

loss of connective tissue in the dermis, scar tissue; thinning associated w/ hypopigmentation

What is crust?

exudate of serum, blood, sebum or purulent material on the surface of the skin “scab”

What is ecthyma?

exudate that involves entire epidermis and accompanied by necrosis of deeper tissues

What is a fissure?

deep split in the skin extending into the dermis, sharply defined w/ vertical walls

What is erosion?

superficial, focal loss of part of the epidermis; heals w/o a scar

What is an ulceration?

focal loss of epidermis extending into the dermis or deeper tissue; heals w/ scar

What is a scar?

fibrous tissue that replaces normal dermal or subcutaneous tissue after skin injury

What is a hypertrophic scar?

do not exceed the margins of the original wound

What is a keloid?

scar extends into surrounding healthy tissue beyond the original wound; harder to manage

What is a comedone?

plug of sebaceous and keratinous material w/in the opening of a hair follicle

What is a milia?

small, 1-2 mm subepidermal keratin cysts that arise from pilosebaceous units or eccrine sweat ducts; hard and fixed

What is a cyst?

circumscribed lesion w/ a wall and a lumen; may contain liquid, solid, or semisolid material

What is a burrow?

narrow, elevated, tortuous channel typically produced by a parasite

What is a linear lesion?

follows a line or specific dermatome

What is an annular lesion?

circular or round

What is a serpiginous lesion?

wavy-border or “snake” like appearance; subset of annular lesion

What are examples of an extensor surface?

elbow, knee

What are examples of a flexor surface?

antecubital fossa, popliteal fossa

What is an intertriginous lesion?

occurring w/in the fold of the skin

What is a Wood’s Lamp?

black light w/ a magnifying glass; used to help dx

What will dermatophytosis illuminate as under a Wood’s Lamp?

yellow/green

What will erythrasma illuminate as under a Wood’s Lamp?

coral

What will porphyria illuminate as under a Wood’s Lamp?

red/pink

What is a dermatoscope?

hand lens w/ built-in lighting and a magnification of 10x to 30x used to see deeper layers not visible to the naked eye

What is diascopy?

special test performed by firmly pressing a microscopic slide over a skin lesion; used to assess erythema vs purpura

What is a Tzanck Smear?

simple, rapid inexpensive test utilized to dx HSV or causes of blistering skin conditions (SJS)

When would you expect to see multi-nucleated cells on a Tzanck smear?

pts w/ Herpes Zoster

What is a KOH prep?

simple method to microscopically identify fungi or yeasts from epidermal skin scrapings, hair roots, or nail clippings

What is patch testing?

dx aid for allergic contact dermatitis

What is photopatch testing?

type of patch test used when contact allergy is suspected that only occurs w/ exposure to sunlight

What is skin prick testing?

allergy test used to identify allergens responsible for triggering sx in Type 1 allergic rxns

What do you need to monitor for when performing a skin prick test?

anaphylaxis

What is acetowhitening?

performed using acetic acid (white vinegar) w/ colposcopy to detect subclinical HPV lesions; + result = blanching/whitening of lesion

What is a skin biopsy?

removal of a sample of skin to identify pathology; can shave, punch, or excision

What are the key questions to ask regarding a pts hx of skin lesions?

Onset, Location, Symptoms, Progression, Evolution, Provocative factors, Previous tx or alleviating factors

What are the ABCDEs of evaluating skin lesions?

Asymmetry, Border, Color, Diameter, Evolving

What 6 key features need to be documented regarding skin lesions?

Primary morphology, Size, Demarcation, Color, Secondary morphology, Distribution

What is the oKoebner phenomenon?

appearance of new skin lesions on previously unaffected skin secondary to trauma

What is the Auspitz sign?

slight scratching or curetting of a scaly lesion reveals punctate bleeding points w/in the lesion; common in psoriasis

What is the Nikolsky phenomenon?

epidermis is dislodged from the dermis by shearing pressure w/ a finger (SSS, TEN, pemphigus vulgaris)

What is the Darier sign?

rubbing or scratching the area of skin affected by mastocytosis results in a redness, swelling, itching, and a palpable wheal