Nipple adenoma arising in a supernumerary mammary gland: a case report.

Nipple adenoma, a benign tumour of the breast, is a relatively rare occurrence. This report describes an even rarer case of nipple adenoma arising within a supernumerary mammary gland. The presenting symptoms were a lump and throbbing pain in the axilla. Ultrasound scan and core biopsy proved inconclusive so surgical excision was undertaken, thus allowing a histological diagnosis. The patient made a full and uneventful recovery. Physicians must be aware that diseases of the breast and nipple-areola complex may also arise in accessory mammary tissue and accessory nipples should not be discounted as a common congenital anomaly. Instead they must be regarded, examined and treated as normal breast tissue.