Зображення 01059. Keratoacanthoma in the upper lid

Keratoacanthoma is a squamous cell tumour that is in principle benign but the histological distinction from a well-differentiated squamous cell carcinoma is often impossible. Keratoacanthoma typically grows in a few weeks, has a hyperkeratinized top and is surrounded by a collar-like rim of skin. The patient is referred for treatment (surgical excision or cryotherapy) without delay because the tumour may grow very rapidly which makes the treatment more problematic.