Mammographic-pathologic correlation of apocrine metaplasia diagnosed using vacuum-assisted stereotactic core-needle biopsy: Our 4-year experience

OBJECTIVE. To determine whether focal apocrine metaplasia of the breast has distinctive mammographic characteristics, we evaluated apocrine metaplasia diagnosed by vacuum-assisted stereotactic core-needle biopsy and correlated mammographic imaging and histopathologic findings. MATERIALS AND METHODS. We retrospectively reviewed our institutional database for records of all vacuum-assisted stereotactic core-needle biopsies performed during a 4-year period. Five hundred thirty-eight lesions were biopsied, of which 302 (56%) were benign. Apocrine metaplasia was diagnosed in 37 lesions. In 11 of these 37 lesions, apocrine metaplasia made up more than 50% of the lesion sampled. RESULTS. On mammography, eight cases (73%) appeared as new or increasing calcifications, and three cases (27%) appeared as new or enlarging equal-density masses (0.6-1.2 cm). Calcifications were heterogeneous in five lesions (63%), amorphous in two (25%), and punctate in one (12%); one heterogeneous cluster of calcifications (12%) also contained milk of calcium. The pattern of calcification distribution was clustered in five lesions (63%), multiple clusters in two (25%), and linear in one (12%). Two masses (67%) were lobular, and one (33%) was round. Two borders (67%) were microlobulated, and one (33%) was circumscribed. CONCLUSION. Apocrine metaplasia is a benign condition commonly associated with other fibrocystic changes. Lesions composed of more than 50% focal apocrine metaplasia are relatively uncommon. A new or enlarging lobular, microlobulated mass or heterogeneous calcification cluster may represent apocrine metaplasia. Because no distinguishing mammographic features are present to require follow-up by imaging, needle biopsy is required for definitive diagnosis.