Introduction to Dermatology Flashcards
Functions of the skin?
- Maintenance of the internal environment
- Protection, e.g: mechanical, heat, cold, light, chemicals, microorganisms
- Metabolic - T4 conversion and vitamin D synthesis
- Communication - social & sexual behaviour
Difference between a macule and a patch?
Macule - flat area of skin that is altered in colour
Patch - flat area of colour change, larger than a macule
Difference between a papule and a nodule?
Papule - elevated, solid, palpable lesion that is ≤1cm in diameter
Nodule - elevated, solid, palpable lesion >1cm
What are erosions?
Sore, due to superficial or partial destruction of surface tissue, such as the skin
What is an ulcer?
FULL-THICKNESS loss of the epidermis with at least a portion of the dermis lost; may extend into the subcutaneous tissue
Ulcers heal with a scar
What are fissures?
A split of the skin
What are vesicles and bullae?
Vesicles - small blister ≤1cm, containing liquid (clear, serous or haemorrhagic)
Bulla - a large blister >1cm and containing liquid (clear, serous or haemorrhagic)
What are pustules?
Circumscribed lesion containing pus, filled with neutrophils
May be white or yellow
NOTE - not all pustules are infected
What is urticaria?
AKA wheal
Transient elevation of the skin due to dermal oedema; usually pale centrally with an erythematous rim and without surface change
Difference between scale and crust?
Scale (AKA hyperkeratosis) - increased in the dead cells of the stratum corneum
Crust - dried liquid
Descriptive terms for scale?
Desquamation - skin coming off in scales
Psoriasiform - large white or silver flakes
Pityriasiform - branny, powdery scale
Lichenoid - apparent scale that is tightly adherent to the skin surface
Keratotic - hormy scale
Exfoliation - peeling scale
Maceration - moist, peeling skin
Verrucous - warty
What is a plaque?
Elevated, circumscribed, palpable lesion >1cm in diameter
What are milia?
Small cysts found under the skin
Explain the process of patch testing?
Commonly used for contact allergic dermatitis
Checked at 28 and 72 hoursq
How to take skin scrapings?
For fungal infection - scrape scale from the edge or take a hair/nail; KOH is used for microscopy/culture
Scabies - lift the mite out with a needle or scrape the burrow after KOH
Uses of skin biopsy?
Diagnosis / excision of malignant lesions
Excision of troublesome benign lesions
Diagnosis of rash
NOTE - make a clinical diagnosis prior to biopsy
