Breast metastasis from cutaneous malignant melanoma mimicking a breast cancer

Breast metastases are very uncommon, either from solid tumors or malignant melanoma.

We present the case of a 42-year-old woman with a history of cutaneous melanoma of the shoulder excised 21 years ago. She presented with a palpable lump in the upper outer quadrant of the right breast. Ultrasound demonstrated a solid mass within a cystic lesion. A core biopsy was taken and first histology reported a poorly differentiated primary breast cancer suspected to be triple negative. MRI detected a satellite lesion in the same breast, a focus of suspected enhancement in the other breast, and the extramammary finding of an enhancing pulmonary lesion. Staging computed tomography detected widespread metastases to the lungs, brain, subcutaneous left shoulder, liver, pancreas, and hepatorenal recess. A core biopsy was taken from the left breast lesion and the previous slides were reviewed; histopathology and immunohistochemistry were in keeping with metastasis from melanoma.

The possibility of a metastatic lesion to the breast should be taken into account in any patient presenting with a breast lump and a previous history of melanoma. Breast involvement cannot be considered an isolated finding, as it might be the first manifestation of widespread disease.