Melanoma Metastasizing to the Breast: A Case Report

BACKGROUND: Melanoma metastasizing to the breast is a rare event, accounting for only 1.3%-2.7% of reported cases. Due to its overlapping clinical and imaging features, it is frequently misdiagnosed as primary breast cancer. CASE PRESENTATION: This study presents a rare case of metastatic malignant melanoma involving the breast. A 49-year-old female was admitted with a palpable mass in the right breast. The breast lesion was classified as BI-RADS 4b. Core needle biopsy initially suggested primary breast malignancy. However, postoperative histopathological examination of the resected specimen revealed positivity for S-100, SOX10, and Ki-67 on immunohistochemical staining, supporting the diagnosis of malignant melanoma. Subsequent physical examination identified a pigmented nevus on the right abdominal wall as the primary lesion. CONCLUSION: Metastasis of malignant melanoma to the breast is uncommon. This case highlights the potential for cutaneous malignant melanoma to metastasize to the breast and underscores the importance of immunohistochemical staining in distinguishing metastatic melanoma from primary breast malignancies.