Accessory breast tissue in the axilla: mammographic appearance.

Mammographic features of normal accessory axillary breast tissue were analyzed in 13 women, 54% of whom had positive findings on physical examination. Radiographically the accessory tissue resembled the remaining normal glandular tissue but was separate from it. The mean radiographic dimension of the accessory tissue, which was best seen on oblique or exaggerated craniocaudal views, was 3.9 cm. In most cases the accessory tissue was either bilateral or confined to the right side. When found on mammography, accessory axillary breast tissue should be recognized as a normal developmental variant rather than considered a pathologic lesion, although carcinoma can develop in the accessory tissue. A specific, radiography-aided diagnosis of accessory axillary breast tissue can eliminate unnecessary biopsy.