Diseases of Skin 1 Flashcards
Melanocytes are derived from which cells?
Neural crest
Where is melanin synthesized? What catalyzes the synthesis?
Melanosomes by tyrosinase
What is the intermediate between tyrosine and melanin?
DOPA
How is melanin transferred from melanocytes to keratinocytes?
Melanosomes
What cells in the skin play a similar role to Langerhans cells?
Dermal dendritic cells
What is a flat circumscribed lesion larger than 5mm?
Patch
What is a flat lesion smaller than 5 mm?
Macule
An elevated flat top lesion smaller than 5mm is? larger than 5mm?
Papule and nodeule
What are vesicles and bulla?
Fluid filled raised lesions smaller and larger than 5mm across respectively
What is a wheal?
Itchy, transient, elevated lesions with dermal edema
What is a result of repeated rubbing on the skin?
Lichenification, thick and tough
What is eschar?
Dead black sloughing skin
Onycholysis is?
When the nail separates from the nail bed
Hyperkeratosis involves thickening of what layer?
Straum corneum
What is hypergranulosis?
Hyperplasia of the stratum granulosum
What is the difference between spongiosis and hydropic swelling or ballooning?
Spongiosis is INTERCELLULAR edema of the epidermis and swelling in INTRACELLULARedema of keratinocytes
What is acanthuses?
Epidermal hyperplasia with thickening of them malphigian layer
What is acantholysis?
Loss of intercellular cohesion between keratinocytes
What is the term for premature keratinization below the stratum granulosum?
Dyskeratosis
Allergic contact dermatitis is what type of reaction? What cells mediate it?
Type 4 hypersensitivity reaction by Langerhans cells and T cells
What is irritant contact dermatitis?
Follows exposure to things capable of DIRECTLY DAMAGING the skin
Mechanisms of irritant contact dermatitis include? (4)
- Keratin denaturation
- Removal of surface lipids and water
- Damage to cell membranes
- Direct cytotoxic effects
What is seborrheic dermatitis?
Chronic dermatitis characterized by redness and scaling in areas where the sebaceous glands re most active
When does seborrheic dermatitis present itself?
Presents in infancy and there is a second peak in audlts
Seborrheic dermatitis has a male or female predominance?
Male
Seborrheic dermatitis is linked with what microorganism>
Malessezia a yeast
Phototoxic reactions are caused by?
UV radiation associated with use of medications leading to formation of toxic photoproducts like free readicals
