Surgical Resection of Metastatic Male Breast Cancer to the Brain: An Illustrative Case Report.

Male breast cancer is rare, accounting for less than 1% of all breast cancers, and central nervous system (CNS) metastases are an uncommon but poor prognostic manifestation. The aim of the current case report is to discuss a 50-year-old man with stage IV estrogen receptor-positive, progesterone receptor-positive, and HER2-positive breast cancer who presented with new-onset focal neurological deficits and was found to have a solitary left parietal brain metastasis with vasogenic edema and midline shift. He underwent gross total resection via craniotomy, with pathology confirming metastatic ductal carcinoma consistent with the primary tumor. Postoperatively, he received adjuvant stereotactic radiosurgery (30-35 Gy in five fractions) to the resection cavity and was transitioned from tamoxifen to trastuzumab deruxtecan (T-DXd) for improved CNS-directed systemic therapy. Surveillance imaging at 6 months demonstrated no intracranial recurrence, and systemic restaging showed no extracranial disease progression. This case highlights the importance of prompt neuroimaging for new neurological symptoms in male breast cancer patients and supports a multimodal strategy, including surgical resection, focal radiation, and CNS-penetrant HER2-targeted therapy, for achieving durable intracranial control in select patients with isolated brain metastasis.