Invasive ductal carcinoma of the breast with signet-ring cell and mucinous carcinoma components: diagnostic utility of immunocytochemistry of signet-ring cells in aspiration cytology materials.

Breast cancer with signet-ring cells is very rare. In this article, we present a case of invasive ductal carcinoma with signet-ring cells and mucinous carcinoma components, which could be diagnosed as a primary cancer by immunocytochemical study of fine-needle aspiration cytology material. A 73-yr-old Japanese woman noticed a palpable mass in the left breast. The aspiration cytology disclosed the monotonous proliferation of signet-ring cell with cytological atypia. The immunocytochemical examination of neoplastic cells showed a positive reaction for estrogen receptor. The extensive examination of body before the operation did not disclose any tumors in other anatomic sites. The histological examination of surgically resected breast tumor showed invasive ductal carcinoma with foci of signet-ring cell and mucinous carcinomas. Finally, our preliminary report suggests that immunocytochemical examination of aspiration cytology materials may provide useful information in searching the primary site of breast carcinoma with signet-ring cells.