SKIN - Seborrhoeic keratosis

This coarsely nodular, very large skin lesion shows microscopically a surface epithelium in which there is proliferation of basal cells and the formation of horn cysts - these are cystic structures lined by flattened epithelium and containing keratin. The underlying tissue is moderately vascular oedematous collagen. The majority of seborrhoeic keratoses rarely exceed 1 cm in diameter.