Hidroacanthoma simplex with in situ porocarcinoma. A case suggesting malignant transformation.

A case of hidroacanthoma simplex, suggesting malignant transformation into porocarcinoma in situ is reported. It represents further evidence that epidermotropic eccrine carcinoma may originate from the acrosyringium. This lesion demonstrates that the upper portion of the dermal eccrine duct may participate in the oncogenesis of hidroacanthoma simplex. It may also provide the missing link in the chain of evolution of benign eccrine poroacanthoma into porocarcinoma.