Metastatic melanoma in the breast and axilla: A case report

Metastatic melanoma of the breast is rare, and demonstrates nonspecific imaging findings which may overlap with both benign and malignant pathology.1–3 Immunohistochemical stains are important to confirm the diagnosis, particularly combining S100, a sensitive marker for melanoma, with more specific tumor markers such as Melan-A and HMB-45, and lack of cytokeratin staining.4–7 We present a case of a 64-year-old female who presented for diagnostic imaging of a palpable abnormality in her right breast, with medical history notable for previously excised cutaneous melanoma, recent COVID-19 vaccination, and significant family history of breast cancer. Diagnostic mammogram of the right breast demonstrated a circumscribed mass in the lower inner quadrant corresponding to the area of palpable concern, as well as an additional non-palpable circumscribed mass in the lower inner quadrant. Targeted right breast ultrasound demonstrated corresponding circumscribed cystic versus solid masses as well as a morphologically abnormal right axillary lymph node. Pathologic results after tissue sampling of the two right breast masses and right axillary lymph node all yielded metastatic melanoma.