Abstract
A 60-year-old woman was consulted with a mass in the right breast. On physical examination a tumor measuring 1.5×1.0 cm was palpable in the right breast C area. Ultrasonogram showed an irregular-shaped tumor and we diagnosed as category 4 by mammogram. Core needle biopsy of the right breast was diagnosed as invasive lobular carcinoma. We performed a breast quadrantectomy of the right breast and a sentinel node biopsy. Pathological findings revealed a tumor consisting of lobular carcinoma with a component containing many signet-ring cell carcinoma, and micrometastasis to the sentinel lymph nodes. Immunohistochemically tumor cells were GCDFP-15-positive and E-cadherin-negative. We diagnosed this case as primary signet-ring cell carcinoma derived from lobular carcinoma. She was followed by postoperative chemotherapy, radiation, and chemoendocrine therapy. We reviewed the cases of primary signet-ring cell carcinoma derived from lobular carcinoma from the Japanese literature with consideration of the characteristics.
