Primary cerebral melanoma of the frontal lobe: a case report and review of the literature

Introduction: Primary cerebral melanoma is an exceedingly rare intracranial neoplasm, accounting for a minuscule fraction of all brain tumors and melanomas. Originating from melanocytes within the central nervous system, its diagnosis is one of exclusion, requiring thorough investigation to rule out metastatic disease from cutaneous, uveal, or mucosal primary sites. Case presentation: We present a 58-year-old male who presented with a recent onset of headaches and right lower limb weakness. Neuroimaging revealed a large, solitary, hemorrhagic mass measuring 5 × 5 cm in the left frontal lobe with significant surrounding edema and a mild midline shift. The patient underwent a craniotomy for gross total resection of the tumor. Histopathological and immunohistochemical analysis (positive for S100, HMB-45, and Melan-A) confirmed malignant melanoma. A comprehensive systemic workup, including dermatological and ophthalmological examinations, endoscopy, and a whole-body PET scan, revealed no evidence of a primary melanoma elsewhere, confirming the diagnosis of primary cerebral melanoma. Clinical discussion: Primary cerebral melanoma remains a significant diagnostic and therapeutic challenge due to its rarity and resemblance to other intracranial lesions. Gross total surgical resection is the cornerstone of treatment and is associated with improved survival outcomes. A definitive diagnosis necessitates a comprehensive systemic evaluation to exclude a metastatic origin. Conclusion: This case underscores the critical importance of considering primary melanoma in the differential diagnosis of solitary brain masses. Complete resection offers the best prognosis, and adjuvant radiotherapy may improve local control. Emerging targeted therapies and immunotherapies hold promise but require further study in primary CNS melanoma.