Premalignant conditions of epidermis

see also SCC

Solar keratosis

Focal area of redness. Scaly uneven areas with an erythematous base

Sun exposed skin


— Prevalence 10% Ireland 57% Australia

Frequently multiple

Natural history long

— Very few progress to SCC (1:100/year)


Alternating columns of parakeratosis (retention of nuclei in keratin layer) & hyper keratosis

Dysplastic cells in atrophic epithelium

Solar damage in dermis


in situ SCC

reddened, scaly raised plaque

Progression to invasion 15-20yrs

5% show invasion @ time of removal

Erythroplasia of Queyrat is carcinoma in situ of glans penis


normal layering lost

replacement by atypical cells

can extend into hair follicles

Cutaneous horn


May be associated with surrounding inflammation

Ca change rare

However, SCC may present as cutaneous horn

Skin 8