Breast cancer with endocrine differentiation: report of two cases showing different histologic patterns.

We report two cases of breast cancer with endocrine differentiation. Case 1 was a 56-year-old woman with a 2-cm tumor in the upper outer quadrant of the right breast and right axillary lymphadenopathy. Excisional biopsy suggested carcinoma and we performed breast-conserving surgery with lymph node dissection. Histologic examination revealed breast cancer with endocrine differentiation resembling small cell carcinoma of the lung, with one nodal metastasis. Case 2 was a 71-year-old woman with a 2.5-cm tumor in the upper outer quadrant of the right breast. Aspiration cytology suggested carcinoma and we performed mastectomy with lymph node dissection. Histologic examination revealed a carcinoid tumor, as one of the breast cancers with endocrine differentiation, but no nodal metastasis. The two patients are now disease-free 26 and 12 months after surgery, respectively.