Invasive primary ductal apocrine adenocarcinoma of axilla: a case report with immunohistochemical profiling and a review of literature.

Primary cutaneous ductal apocrine adenocarcinoma (PCDAA) is a rare malignant cutaneous neoplasm usually arising in areas of high apocrine gland density. There have been a total of 40 cases of primary apocrine adenocarcinoma reported in the literature; many are indolent and slowly- developing, but some are rapidly progressive. Primary cutaneous ductal apocrine adenocarcinoma has distinctive histologic and immunohistochemical characteristics and the treatment of choice for PCDAA is wide local excision with clear margins. Sentinel lymph node biopsy (SLNB) has also been used to determine prognosis and management. We present a case of a 92-year-old female with a 1-year history of a subcutaneous tumor of the right axilla, histologically consistent with a diagnosis of PCDAA arising in an accessory nipple. To our knowledge this is the first reported case of apocrine adenocarcinoma to develop in an accessory nipple.