Secretory carcinomas of the breast are very rare and represent 0.1% of all breast carcinomas. We experienced a case of the disease whose preoperative diganosis was mammary cyst or fibroadenoma. A 68-year-old woman was seen at the hospital because of a 1.0×1.0 cm painless tumor in the A area of the left breast. On palpation, MMG, and ultrasonography, most probable diagnosis was mammary cyst or fibroadenoma. To obtain the definitive diagnosis, an extirpation biopsy was carried out under local anesthesia. The specimen disclosed typical features of secretory carcinoma; irregular tubuloaveolar arrangement and active secretion of PAS and Al-b staining positive material was found microscopically. A radical mastectomy was performed. When no axillary lymph node metastasis was found. There has been no sign of recurrence as of about 2 years after the operation.
Secretory carcinomas of the breast are said to have favorable prognosis compared with other breast cancers and are often indicated more limited surgery (breast-conserving surgery). As to lymph node metastases, however, there was no significant difference between T1 secretory carcinomas and other breast cancers; the frequency of metastases was 15.4% versus 17.6%, respectively. This fact suggests that mastectomy with axillary lymph node cleaning at least is recommended for the initial treatment of secretory carcinomas of the breast.