Skin Flashcards
Hyperkeratosis
More keratin = more cells in S. corneum.
Psoriasis and Lichen planus.
Parakeratosis
Retained nuclei in S granulosum, thinning, more turnover.
Psoriasis and dandruff.
Acanthosis
Thickening of S spinosum
Acantholysis
Lose desmosomes, so less cohesion between keratinocytes.
Pemphigus vulgaris.
Spongiosis
Intercellular oedema in epidermis.
Vesicles in eczema (dermatitis).
Histology of eczema/dermatitis
Acute: spongiosis, inflam infiltrate in dermis, dilated capillaries.
Chronic: acanthosis, crusting, scaling.
Clinical features of Atopic dermatitis (eczema)
Infants: face & scalp.
Children+ : Flexural areas. Lichenification if chronic.
Features of Contact dermatitis (eczema)
Erythma, swelling, pruritis.
Type IV hypersensitivity (nickel, rubber…), so affects ear lobes, neck, wrist, feet.
Features of Seborrhoeic dermatitis
Inflammatory reaction to the yeast Malassezia.
Infants: cradle cap.
Adults: mild erythema, fine scaling, mild pruritus - eyebrows, eyelids, ears, chest.
Layers of epidermis
S. corneum,
S. granulosum,
S. spinosum,
S. basale.
Histology of Psoriasis
Parakeratosis,
loss of S granulosum,
clubbed rete ridges ("test tubes in a rack"),
Munro's microabscesses.
Proliferation.Associated features of Psoriasis
Nail changes: Pitting, Onycholysis, Subungual Hyperkeratosis;
Arthritis.
Psoriasis - commonest form, with appearance
Chronic plaque psoriasis.
Salmon pink plaques, silver scale, outside of knees, elbows, scalp.
Auspitz’ sign
Pin-point bleeding in psoriasis
Koebner phenomenon
Linear lesions after trauma.
Seen in Psoriasis & Lichen planus (scratching),
and linear exposure to Molluscum & Warts.
Lichen planus lesions
Pruritic, Purple, Polygonal, Papules, Plaques.
Mother of pearl sheen, Wickam’s striae.
Histology of Lichen planus
Hyperkeratosis,
saw-toothing of rete ridges,
basal cell degeneration.
Erythema multiforme appearance
Annular target lesions on hands and feet.
Pleomorphic (varied) lesions.
Causes of Erythema multiforme
Infections: HSV, mycoplasma;
Drugs: penicillin, salicylates, anti-malarials.
Nikolsky’s sign
Exfoliation with light rubbing.
Seen in TEN/SJS and pemphiguS.
Sheets of skin detachment,
Stevens Johnson Syndrome
Sheets of skin detachment, >30% body SA
Toxic Epidermal Necrolysis
Causes of SJS/TEN
Drugs: sulfonamide Abx, anticonvulsants.
Pityriasis rosea
Salmon pink rash (herald patch), then oval macules in Christmas tree distribution.
After viral illness.
Remits spontaneously.
