Apocrine cystadenoma arising in a nevus sebaceus of Jadassohn.

An increased incidence of benign and malignant adnexal tumors has been noted to occur within the nevus sebaceus of Jadassohn. We report a case of a 41-year-old white woman with a blue cyst on her scalp which had recently developed within a congenital "birthmark." Excision of the lesion revealed that the nodule was an apocrine cystadenoma within a nevus sebaceus of Jadassohn. The clinical features of nevus sebaceus with apocrine cystadenoma are discussed and the various tumors which may arise within the nevus sebaceus are reviewed.