Abstract
A 41-year-old woman presented with a 9-month history of subcutaneous mass in the right axilla. The mass gradually increased in size over time. Dermatological examination found a mobile, elastic-soft, well-demarcated subcutaneous mass measuring 3 cm in diameter in the right axilla. The lesion was excised. Histologic examination showed proliferation of connective tissue with an adenoma component of glandular ducts and surrounding accessory breast tissue, yielding a diagnosis of fibroadenoma arising in the axillary accessory mammary gland. Fibroadenoma arising in an axillary accessory mammary gland should be included in the differential diagnosis when an axillary tumor is found, even though it is a rare clinical entity.
