-Case Report-

Melanoma Metastasis to the Left Breast: A Case Report

Megumi Sano¹, Keiko Yanagihara¹, Mio Yagi¹, Koji Nagata² and Hiroyuki Takei³

¹Department of Breast Surgery and Oncology, Nippon Medical School Tama Nagayama Hospital, Tokyo, Japan
²Department of Pathology and Diagnosis, Nippon Medical School Tama Nagayama Hospital, Tokyo, Japan
³Department of Breast Surgery and Oncology, Nippon Medical School, Tokyo, Japan

Metastatic breast tumors are rare and often misdiagnosed as primary breast cancer. Herein, we present a case of breast metastasis from malignant melanoma. A 46-year-old woman presented to our department with a lump in her left breast. Examination revealed a relatively soft mass measuring 4 cm in diameter in the left breast. A needle biopsy was performed, and immunostaining for S-100, human melanoma black-45, CD56/neural cell adhesion molecule, and Melan-A confirmed a diagnosis of malignant melanoma. The metastasis was confined to the breast and was thus treated by surgery to excise the tumor. Malignant melanoma is a rare disease in the Japanese population and is associated with a poor prognosis because of the risk of early metastasis to multiple organs and lymph nodes. However, when complete resection of distant metastases is feasible, curative resection may be indicated. Herein, we report a case of breast metastasis from malignant melanoma and review previously published case reports on this rare condition.

J Nippon Med Sch 2026; 93: 101-105

Keywords
melanoma, breast neoplasms, prognosis, metastatic breast tumor

Correspondence to
Megumi Sano
m-sano@nms.ac.jp

Received, July 29, 2024
Accepted, November 27, 2024