Apocrine hidrocystoma--a report of five cases and review of the Japanese literature.

Five cases of apocrine hidrocystoma are reported. One is multiple and the others are solitary lesions. There are more than 60 cases reported in the Japanese literature. Apocrine hidrocystomas usually occur as a solitary lesion. Only two cases of multiple apocrine hidrocystoma have been described so far in Japan. We reviewed the literature and discussed the clinicopathologic nature of this tumor. Apocrine hidrocystomas are usually composed of a cystic cavity lined by columnar epithelium, showing apocrine type secretion. Peripheral to this, myoepithelial cells are usually seen; however, they were absent from all of the present cases. Change in hue of the tumor is another characteristic feature. About half of the reported Japanese cases exhibited distinctive coloration, variously light brown, red-brown, or bluish. In contrast, non-Japanese cases tended to have darker coloration.