Metastatic Meningioma: Neuroradiologic and Molecular Imaging Perspectives.

Meningiomas are the most common primary central nervous system tumors, arising from arachnoid cap cells and typically following a benign clinical course. However, a minority of cases-particularly higher-grade meningiomas-exhibit aggressive behavior, including local invasion, recurrence, and, in rare instances, extracranial metastasis. Metastatic meningioma, defined as dissemination beyond the cranial and spinal compartments, remains exceptionally uncommon, with reported incidence ranging from 0.1% to 0.76%. Common metastatic sites include the lungs, bone, liver, and lymph nodes, although virtually any organ may be involved. Proposed mechanisms of spread include hematogenous dissemination via venous sinuses, cerebrospinal fluid seeding in high-grade variants, and possibly lymphatic dissemination. Imaging features that suggest metastatic potential include irregular margins, heterogeneous enhancement, prominent peritumoral edema, and bone destruction. Advanced modalities, such as gallium 68 DOTA-Tyr3-octreotide PET/CT and fluorine 18 fluorodeoxyglucose PET, play an increasing role in detecting and characterizing both known and occult metastatic lesions. Molecular alterations, including