Metastases to the Male Breast: A Systematic Review

Background/Objectives: Breast metastases originating from extramammary malignant tumors represent an exceptionally rare clinical entity, particularly in the male population. This study aims to review relevant literature on secondary breast involvement in male patients, focusing on clinical presentation, imaging features, histological and immunohistochemical characteristics and management strategies. To date, no published systematic review focusing on this topic exists in the international literature. Methods: A systematic review of the available literature was conducted through a comprehensive search of the PubMed/MEDLINE database up to December 2025. A total of 376 records were identified, of which 98 articles met the inclusion criteria and were included in the analysis. Results: A total of 192 cases were identified, mainly from case reports and small case series. The mean age was 58 years, with similar distribution between breasts and occasional bilateral involvement. Breast metastases often occurred months to years after the primary tumor (mean 32 months) and typically indicated advanced disease with additional metastases. The most common primary tumors were prostate, lung, and melanoma. Diagnosis relied on biopsy with histological and immunohistochemical evaluation. Management was primarily directed at the underlying systemic disease, while surgery, although frequently performed, contributed mainly to diagnostic confirmation and local disease control. Conclusions: Histological identification and immunohistochemical characterization are crucial in the differential diagnosis between primary breast carcinoma and metastatic disease to the breast. The diagnosis of a metastatic lesion, rather than a primary breast malignancy, alters the therapeutic approach.