The intra-epidermal epithelioma of Jadassohn: a distinct entity.

Forty cases of a distinctive acervate epidermal tumour (intra-epidermal epithelioma of Jadassohn) are described. The pathological and clinical features distinguishing it from other skin tumours are emphasized. Invasive areas were found in five of the cases, one with metastasis to a lymph node, underlining the need to differentiate this tumour from benign epidermal tumours, such as 'irritated' seborrhoeic keratosis and inverted follicular keratosis with which it has been and still is frequently confused.