Papillary eccrine adenoma.

A 28-year-old man came to us with a solitary skin colored, mildly tender nodule of 6 months duration on the dorsum of the right hand. On histological examination, multiple dilated ducts without apparent continuity with the surface were found in the dermis. These dilated ducts had branching tubules with eosinophilic amorphous material filling most of the lumina. The peripheral cells of the tubules resembled myoepithelial cells, whereas the luminal border cells were cuboidal or low columnar. Papillary projections arising from the inner cells were seen extending into the lumen. These features were diagnostic of a rare tumor, papillary eccrine adenoma.