Pathoma - Skin - Tumors, Pigment, Infection Flashcards
Describe the appearance of seborrheic keratosis
Flat, greasy, pigmented squamous cell proliferation with keratin-filled cysts (horn cysts)
Looks “stuck on”
Describe histology of seborrheic keratosis
Keratin psuedocysts
What is Leser-Trelat sign?
Sudden onset of multiple seborrheic keratoses
Suggestive of underlying carcinoma of the GI tract
What are the two disease associations of acanthosis nigricans
Insulin resistance (e.g. diabetes, obesity, Cushing’s)
Malignancy (especially gastric carcinoma)
What is the most common skin cancer
Basal cell carcinoma
Describe the apperance of basal cell carcinoma
Elevated nodule with central, ulcereated crater surrounded by dilated vessels (rolled borders)
“pink, pearl-like papule”
Describe histology of basal cell carcinoma
Nodules of basal cells with peripheral palisading
Prognosis of basal cell carcinoma?
Good - metastasis is rare
What is xeroderma pigmentosum
Autosomal recessive defect in enzymes required for nucleotide repair
Inability to repair pyrimidine dimers caused by UV rays
Describe the histology of squamous cell carcinoma
Keratin pearls
Describe common location of basal cell carcinoma vs. squamous cell carcinoma
Basal cell - upper lip
Squamous cell - lower lip
What is actinic keratosis and what is an important complication?
Scaly plaque that is a precursor of squamous cell carcinoma
What is keratoacanthoma?
Well-differentiated squamous cell carcinoma that develops rapidly and regresses spontaneously
What embryonic structure are melanocytes derived from?
Neural crest
Describe synthesis and distribution of pigment
Melanocytes synthesize melanin in melanosomes using tyrosine, and then pass melanosomes to keratinocytes
What is the defect in vitiligo?
Localized loss of skin pigmentation due to autoimmune destruction of melanocytes
Describe the defect in albinism
Congenital lack of pigment due to enzyme defect (e.g. tyrosinase) that impairs melanin production
What is the cause of freckles?
Increased number of melanosomes (melanocytes are NOT increased)
What is melasma and its associations
Mask-like hyperpigmentation of the cheeks
Associated with pregnancy and oral contraceptives
Differentiate between junctional, compound, and intradermal nevus
Junctional - nest of melanocytes at the dermal-epidermal junction
Compound - nests at the junction grow into the dermia
Dermal - dermal-epidermal nest is lost and there are just melanocytes within the dermis
Appearance of junctional vs. dermal nevus
Junctional - flat macules
Dermal - papular
What are the ABCs of melanoma
A - Asymmetry
B - irregular Borders
C - Color is not uniform
D - Diameter > 6 mm
E - Evolution over time
Describe radial vs. vertical growth of melanoma
Radial - horizontal growth along epidermis and superficial dermis (low risk of metastasis)
Vertical - growth into deep dermis (increased risk of metastasis - Breslow thickness)
Cause of Staphylococcal scalded skin syndrome
Exfolatin A and B toxin result in epidermolysis of stratum granulosum
Differentiate staph scalded skin syndrome from toxic epidermal necrolysis
SSSS - epidermolysis at stratum granulosum (superifical skin sloughing)
TEN - epidermolysis at dermal-epidermal junction (deeper sloughing)
Describe histology of Molluscum contagiusum
Cytoplasmic inclusions within keratinocytes (molluscum bodies)
