Eccrine porocarcinoma shares dermoscopic characteristics with eccrine poroma: A report of three cases and review of the published work.

Eccrine porocarcinoma (EPC) is a rare malignant skin tumor presumably arising from the intraepidermal ductal portion of the sweat gland. EPC occasionally mimics eccrine poroma (EP), seborrhea keratosis (SK), basal cell carcinoma (BCC), pyogenic granuloma (PG) and amelanotic melanoma with its clinical appearance as a pink nodule. Dermoscopy is an invaluable technique in diagnosing skin tumors. However, few cases of EPC have been reported using dermoscopic images, and their details were not well examined. Here, we present three histopathologically proven cases of EPC and summarize their dermoscopic findings together with five previously reported cases. None of the eight cases showed dermoscopic evidence indicative of SK (comedo-like openings, milia-like cysts, fissures and ridges, and hairpin vessels with white halo), BCC (blue-gray ovoid nests, multiple blue-gray globules, wheel-like structures, shiny white areas, leaf-like areas and arborizing vessels) or PG (reddish homogeneous area with collarette and white rail lines). A milky red area, which was suggestive of amelanotic melanoma, was not detectable in any cases. Seven cases exhibited a polymorphous vascular pattern mainly consisting of hairpin, linear-irregular and dotted vessels. A combination of round-to-oval pink-white structureless areas and white-to-pink halo was observed in five of eight cases, with one case showing the white-to-pink halo alone. Our investigation revealed that the dermoscopic characteristic of EP was also observed in discrete areas of EPC lesions. Thus, it is possible that the histopathological architecture of EPC contains portions of benign EP-like components. Awareness of this dermoscopic aspect of EPC may be helpful when diagnosing pink nodules.