Challenges in Managing Brain Metastases From Merkel Cell Carcinoma in an Immunosuppressed Patient: A Case Report.

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine tumor with high rates of metastasis and poor prognosis. While MCC commonly metastasizes to the lymphatic system, distant central nervous system (CNS) involvement is unusual, often complicating early detection and treatment. We describe the case of a 58-year-old male with multiple comorbidities who presented with progressive left-sided weakness and disorientation. Imaging revealed a right frontal lesion with mass effect, and further scans identified an iliac and inguinal lymphadenopathy without a primary skin lesion. The initial inguinal lymph node biopsy was inconclusive, prompting surgical resection of the brain lesion. Histopathology confirmed neuroendocrine carcinoma with CK20 dot-like positivity, consistent with MCC. Despite interdisciplinary management, the patient experienced multiple complications, including a respiratory infection and progressive systemic deterioration, ultimately succumbing to septicemia. MCC with CNS metastasis is a rare and highly lethal condition. This case underlines the importance of early recognition and aggressive multidisciplinary management for potential improvement in prognosis, despite limited therapeutic options.