Mammary synchronous mucinous cystadenocarcinoma and columnar cell mucinous carcinoma: a case report

Mucin-producing carcinomas are unusual primary malignancies of breast, and constitute about 1-4 percent of total breast cancer. The mammary mucin producing carcinomas are divided into 4 histologic subtypes according to WHO classification, including mucinous carcinoma, mucinous cystadenocarcinoma (MCA), columnar cell mucinous carcinoma (CCMC), and signet ring cell carcinoma. However, the synchronous primary MCA and CCMC of breast is a very rare case presentation. The case reported a 56-year-old female, who presented with right mammary lumps and nipple discharge about 1 year. Imaging examinations revealed multiple cystic and solid nodules in upper outer quadrant of right breast, associated with ectatic ducts. Serum levels of tumor markers were normal. Right mammary lumpectomy revealed mucinous carcinoma, modified radical mastectomy, and lymph node dissection were carried out. For neoplastic cells, ER and PR were positive, HER2 (1+) was negative, Ki67 was low expression (3-5%). There was no metastatic carcinoma in lymph nodes (0/8). Modified radical mastectomy and lymph node dissections were carried out. Tamoxifen was chosen for adjuvant therapy. After a 3 month follow up, the patient survived without recurrences and distant metastasis. We report the first synchronous primary MCA and CCMC of breast with molecular subtype of Luminal A.