Cutaneous horn (Q52402)

Cutaneous horn is a clinical morphological description for a firm, white or yellow conical horn-like protuberance arising from the skin surface. Abnormal keratinization of the underlying epidermis produces variable acanthosis beneath a vertically-orientated column of compacted cornified cells. The underlying epidermal derangement may be due, amongst other things, to actinic keratosis, squamous cell carcinoma, viral wart or seborrhoeic keratosis. Actinic keratosis is, however, the commonest underlying disorder.