Malignant metastatic melanoma in brain with unknown primary origin: a case report.

Introduction: Melanoma, a malignant tumor derived from neural crest melanocytes, predominantly affects the skin but can involve any organ with neural crest migration. Metastatic melanoma of unknown origin, particularly when it involves the brain, is associated with significant morbidity, mortality, and a typically poor prognosis.

Case presentation: The authors present a 71-year-old man with a history of hypertension and seizure disorder who experienced a headache, transient loss of consciousness, and vomiting. Imaging revealed a mass with perilesional edema in the right temporal, right occipital, left frontal, and left periventricular regions. A craniotomy and excision of the right temporal lesion confirmed malignant metastatic melanoma through histological examination. Despite normal findings in skin, mucosal, anogenital, and ophthalmological examinations, and a comprehensive CT scan of the chest, abdomen, and pelvis that revealed no primary tumor, the diagnosis of metastatic melanoma of unknown origin was made. The patient did not receive treatment due to financial constraints.

Clinical discussion: About 2-6% of melanoma patients present with tumors of unknown primary origin. Brain metastases occur in ~60% of advanced melanoma cases and carry a high risk of spontaneous bleeding. While traditional survival rates are low, surgical resection, stereotactic radiosurgery, immunotherapy, and BRAF/MEK inhibitors can improve outcomes.

Conclusion: Headaches, lethargy, vomiting, and altered sensorium should prompt investigation for brain metastases from melanoma, even without a detectable primary tumor. Treatment strategies including immunotherapy and stereotactic surgery aim for a median survival of 8-10 months. Socio-economic factors, as highlighted in this case, significantly affect treatment access and patient outcomes.