Eccrine porocarcinoma arising within an area of Bowen disease.

Summary Very little is known about the aetiology of eccrine porocarcinoma (EP), a rare malignant sweat-gland tumour. Most reported cases have arisen de novo, or from a benign eccrine poroma. We report an unusual case, in which eccrine porocarcinoma arose at the exact site of pre-existing Bowen disease (BD).