[Pleomorphic Invasive Lobular Carcinoma Developed after Surgery for Simultaneous Ipsilateral Multiple Cancers]

We report a case of pleomorphic invasive lobular carcinoma that developed after surgery for multiple ipsilateral cancers. The patient was a 54-year-old woman who visited our hospital after a tumor-like lesion was noted in her right breast. A needle biopsy revealed that the patient had invasive ductal carcinoma. No obvious distant metastasis was found;therefore, circular mastectomy and axillary lymph node dissection were performed. Histopathological examination revealed the following tumors;Tumor 1:Invasive ductal carcinoma(solid type), tumor diameter 33 mm, ER negative, PgR negative, HER2 negative, Ki-67 20.4%;and Tumor 2:Invasive lobular carcinoma, tumor diameter 6 mm, ER negative, PgR negative, HER2 negative, Ki-67 30.2%. The resection margin was negative, and lymph node metastasis was diagnosed as 3/12. Postoperative chemotherapy, radiation therapy, and endocrine therapy were performed. One year and 6 months after surgery, a hard lump was found in the remaining breast, and a needle biopsy confirmed it as pleomorphic lobular carcinoma. A pectoral muscle- sparing mastectomy was performed. Pathological examination of the excised specimen revealed new breast cancer:a pleomorphic lobular carcinoma, with tumor diameter 22 mm, and multiple daughter nodules. The resection margins were negative. The results were ER negative, PgR positive, HER2 negative, and Ki-67 25%. As the prognosis and treatment of invasive lobular carcinoma was unclear, caution was required.