Primary intracranial malignant melanomas in solitary type: a tertiary center experience

Solitary type primary intracranial malignant melanoma (PIMM) is extremely rare but fatal. The optimal treatment algorithm according to clinical relevance of symptoms and outcomes is unclear. This series emphasized the prognostic factors of solitary PIMM and established the treatment algorithm for this rare disease.Patients with solitary PIMMs were pathologically verified and treated with neurosurgical tumor resection. All solitary PIMMs recruited at our institute received multidisciplinary team care. We analyzed the clinical findings and prognostic factors.The study cohort included 10 patients. PIMMs in solitary type impacted middle-aged populations with male predominance in Taiwan. Most patients (80%) presented a single tumor initially. Six patients had progressed to multiplicity after the initial treatment. Rates of tumor bleeding and leptomeningeal metastasis seeding (LS) are high in solitary PIMMs. Patients who had gross-total resection (GTR) had better survival than those who had incomplete resection, with median overall survival (OS) rates of 170.4 months vs. 5.23 months (p = 0.004). Multiplicity, eloquent area involvement, initial tumor bleeding, LS, hydrocephalus, and Karnofsky Performance Score 80 at diagnosis were associated with negative outcomes in progression-free survival and OS. Adjuvant radiotherapy for patients who had LS and for those who cannot undergo grossly total tumor removal resulted in a good outcome.GTR demonstrated better outcomes for solitary PIMM. For recurrent tumors, aggressively repeated surgical resection remained beneficial for selected cases. Adjuvant radiotherapy was a treatment option for LS following operation. We proposed a possible treatment algorithm for solitary PIMM.