Primary intracranial malignant melanomas: A case series with literature review.

Rationale: There is a high chance of misdiagnosis and limited knowledge regarding therapeutic strategies owing to the rarity of primary intracranial malignant melanoma (PIMM). The objective of the present study was to evaluate the clinical features, treatment modalities, and outcomes of patients with histologically proven PIMM.

Patient Concerns: Data of 15 patients with PIMM admitted to the Chinese People's Liberation Army General Hospital in a 14-year period between January 2005 and January 2019 were collected. Clinical presentations, pathology, surgical strategies, adjuvant treatment, and prognosis were retrospectively analyzed.

Diagnoses: CT showed iso- or high-density lesions in 12 cases (80%). MRI revealed short T1 and slightly short T2 in 14 cases (93.3%).The tumors showed mild or no enhancement on enhanced MRI. The patients were eventually diagnosed with PIMM through pathological examination.

Interventions: The treatment modalities included radical resection followed by conventional radiotherapy (RT, n = 12) and subtotal resection followed by stereotactic radiosurgery (n = 3).

Outcomes: All 15 patients had either recurrence or metastasis at an average of 14.7 months (range, 6-23 months) after surgery. In total, 14 patients (93.3%) succumbed to disease, with a mean overall survival of 22 months (range, 6-36 months). The median survival time was 23 months. The overall survival rates at 1, 2, and 3 years were 80, 47, and 13%, respectively. Radical resection with RT was associated with longer overall survival (log-rank, P < .05) than subtotal resection followed by stereotactic radiosurgery.

Lessons: PIMM is an extremely rare tumor with a poor prognosis. Radical resection with RT may result in a longer overall survival rate. Targeted immunotherapy may be a promising treatment option for PIMM.