A study of 42 patients with 50 apocrine hidrocystomas (cystadenomas) revealed that this entity is rarely diagnosed clinically and is most frequently misdiagnosed as basal cell epithelioma. These skin-colored, blue or translucent cysts usually can be distinguished from basal cell epitheliomas, nevi, and other lesions if the diagnosis comes to mind. Apocrine hidrocystomas are histologically characteristic and are indistinguishable from retention cysts of the glands of Moll.