The diagnostic dilemma of primary central nervous system melanoma

Melanomas are malignant neoplasms of melanocytes developing predominantly in the skin, but occasionally arising from eyes, mucous membranes, and the central nervous system (CNS). The CNS can be affected by a spectrum of melanocytic lesions ranging from diffuse neurocutaneous melanosis, to a focal and benign neoplasm (melanocytoma), and to an overtly malignant tumor (melanoma). Primary melanocytic lesions involving the CNS are typically concentrated in the perimedullary and high cervical region. Primary CNS melanoma cannot be reliably distinguished from metastatic melanoma on neuroimaging and histopathological characteristics alone: its diagnosis is established only after exclusion of secondary metastatic disease from a cutaneous, mucosal or retinal primary. We present two patients with primary CNS melanoma and discuss relevant issues, available treatment options, and expected outcomes. Awareness of disease spectrum and clinico-biological differences may be used to guide therapeutic decision-making for a patient with a proven or suspected primary CNS melanoma.