Dermatology Flashcards
Cardinal features of skin examination
Distribution of lesions, arrangement/patterns of lesions, morphology of the lesion (shape, size, color, texture, primary vs. secondary)
Distribution of lesion includes
Extent- localized, regionalized, generalized, universal
Pattern- symmetry, photodistributed, follicular,
Location- flexural, extensor, palm/soles, scalp, joints, mucous membranes
Dermatomal pattern
Distribution of the sensory innervation
Herpes Zoster
Grouped arrangement
Clustered within a focal area
Herpes simplex
Linear arrangement
Often due to external phenomena
Poison ivy- contact dermatitis
Morphology shape- ring like with central clearing
Annular
Ringworm
Morphology shape- central depression or dell
Umbilical
Molluscum
Oval morphology example
Pityriasis rosea
Round or nummular morphology example
Discoid lupus or nummular eczema
What determines color of skin morphology?
Endogenous factors- melanin, hemoglobin
Exogenous factors- chemicals (carotene from food and Lycopenic acid from tomatoes) and deposition of material like iron, drugs
White morphology
Loss of melanin or hemoglobin
Increase in collagen/scar
Vitiligo
Brown morphology
Melanin in epidermis or papillary dermis, iron or increased thickness of skin
Melanocytic nevus
blue morphology
Dark substance or cells in dermis or subcutaneous- melanocytes, iron, medicine
Minocycline pigmentation
Red morphology
Capillaries- pyogenic granuloma (eroded capillary hemangioma
blood
Yellow morphology
Lipid- localized, Xanthelasma
Bilirubin and beta-carotene- generalized
Black morphology
Excessive Melanin- dysplastic nevus and melanoma
blood
Translucent- clear/shiny morphology
Clear cells in skin- basal cell carcinoma
Fluid collection- eccrine cyst
Brown, black and blue morphology (collectively)
Melanin deeper than epidermis- often a sign of malignant melanocytes
Melanoma
Black and red morphology
Blood in superficial dermis- purpura
Texture morphology- dry, white, adherent
Scaling- cutaneous lupus
Examples of primary lesions
Macule/patch Papule/plaque Nodule Vesicle/bulla Pustule
Secondary lesions and differences
Erosion- loss of some epidermis, superficial
Ulcer- loss of complete epidermis, deep loss of skin involving dermis or subcutaneous fat
Fissure- linear split in skin
Eschar- scar/crust on top of lesion
Scratch
Excoriation- erosion or ucler caused by scratching
Flat lesions- not palpable, no loss of substance, differs from surrounding skin because of color, smooth or scaling
Macule- small
Patch- greater than 1 cm
Raised lesions- palpable due to space occupying substance of cells in skin
Papule: 1-5mm
Plaque: greater than 5mm, SA>height
Nodule: deeper, >5mm, height>SA
Tumor: larger nodule used to describe neoplasm
Fluid filled spaces
Vesicles- clear fluid or blood filled, <5mm diameter
Bulla- fluid filled, larger than 5mm
Pustules- whitish yellow in color, filled with pus (neutrophils or eosinophils) not automatically infection, caused by hypersensitivity, physical trauma, autoimmune, genetic, etc
Secondary lesion atrophy types
Thinning or wasting of one or all layers of skin
Epidermal- topical or injectable steroids
Dermal- age
Subcutaneous- HIV, injection
Clinical description of exam
Distribution, pattern, then morphology
Ex) involving the face, torso, extremities
Scattered, multiple, discrete and confluent
1-20cm well defined red thick scaling plaques
Scraping lab tests
KOH prep for yeast/fungi
Cytologic prep (Tzanck smear) in vesicular eruptions to check for infection with virus
Mineral oil prep for scabies mite, eggs, feces
Other lab tests
Bacterial, viral, fungal cultures
Skin biopsy for histology, immunoflourescence or culture
Patch test for contact dermatitis
