Tumors may arise on other areas of the head, neck, and trunk. Tumors also have been reported to occur on the penis, in the axillae, and in the anal region. Lesion edges are not well delineated but blend gradually into adjacent skin. Walls, although translucent, are sufficiently thick that they seldom rupture spontaneously. When incised, the cyst collapses and a thin, clear, brownish or blackish fluid is released.
Cysts are mobile with palpation and transilluminate.
The fluid color of an apocrine hidrocystoma does not result from the presence of melanin or hemosiderin but may result either from the Tyndall phenomenon or the presence of lipofuscin pigment. Although the origin of apocrine hidrocystomas is not known entirely, they are believed to be adenomatous cystic proliferations of the apocrine glands. Apocrine hidrocystomas are more likely to be multilocular than the closely related eccrine hidrocystoma. The cyst wall is lined by apocrine-type secretory epithelium. The nuclei of these cells are positioned basally.