Eccrine porocarcinoma: a rare but sometimes fatal malignant neoplasm.

A 79-year-old woman presented with an asymptomatic reddish nodular lesion, present for over 1 year, 2.5 cm in diameter on the dorsum of her left hand. Approximately 1 year earlier, the lesion, clinically diagnosed as seborrheic keratosis, had been treated with diathermocoagulation not followed by histopathologic examination. The patient reported that at that time the lesion was slightly raised and had a scaly surface. After treatment, the lesion had reappeared in a few months, becoming wider and wider. The lesion appeared as an erythematous nodule, with a scaly crusty surface (Figure 1). The patient reported that at the onset there had been the slow growth of an erythematous patch on which the nodular lesion had developed in 3 months.