Non-retroareolar male mucinous breast cancer without gynecomastia development in an elderly man: A case report

Abstract

Background: Male breast cancer (MBC) is an extremely rare condition and accounts for less than 1% of all breast cancers, and malignant tumors occur in less than 1% of the affected men. Mucinous breast cancer is extremely rare and accounts for 2% of all invasive breast cancers. Generally, MBC is accompanied by a retroareolar mass.

Case summary: Herein, we report a case of male mucinous breast carcinoma (MMBC) without gynecomastia development and with mass localization outside the common retroareolar region, wherein the mass was a painless nodule in the right breast of a 64-year-old man. We also discuss the clinical and pathological characteristics of this unusual tumor. The excised breast specimen showed pure mucinous carcinoma. The patient had strong expression of estrogen and progesterone receptors, a low Ki-67 proliferation index of the tumor cells, and negative pathological axillary lymph nodes. The patient underwent modified radical mastectomy and axillary lymph node dissection, followed by tamoxifen hormone therapy.

Conclusion: To the best of our knowledge, this is the first case report of MMBC in the non-retroareolar region of the nipple without gynecomastia development. Mucinous tumors are easily missed during diagnosis, and the incidence of axillary lymph node metastases of chest mucinous tumors has increased.

Keywords: Breast cancer; Case report; Male; Mucinous adenocarcinoma; Nipple.

Figure 1

Preoperative and postoperative imaging corresponding surgical specimen and pathology analysis. A: Ultrasound image of the left breast region at the upper outer area of the nipple demonstrating a 1.88-cm oval, parallel isoechoic mass; B: Surgical specimens showing the position of the surgical scar; C: Computerized tomography reveals posterior nipple glands (the arrow points to the position where the back of the nipple is located); D: Postoperative defects from outpatient surgery (the arrow points to the location of the residual cavity after removal of the mass); E: Histopathological examination of the excised breast tissue showing a nodular lesion with relatively clear borders in the breast. Homogeneous clusters of tumor cells containing small nuclei together with slightly larger round nuclei were suspended in abundant mucus material (mucus lake). The tumor invaded the surrounding adipose tissue and muscle tissue and did not invade the skin or subcutaneous tissue. The ductal tissue of the breast was visible in the periphery, and no intraductal cancer changes were seen (hematoxylin-eosin, 200 ×); F: Pathology of the nipple and posterior nipple, and no cancerous tissue invasion was seen in the nipple and subpapillary ducts, and Paget’s changes were not seen in the skin (hematoxylin-eosin, 20 ×).

Figure 2

Pathology and immunohistochemistry analysis. A: Image showing clusters of tumor cells suspended in abundant extracellular mucin and separated by ciliated fibrous intervals containing capillaries; B: Estrogen receptor (2+); C: Progesterone receptor (2+); D: AR (−); E: Ki-67 (5%); F: CerbB-2 (−) (scale: 100 μm; 200 ×).

Figure 3

Timeline of disease course.