Uncommon Cranial Meningioma: Key Imaging Features on Conventional and Advanced Imaging.

Given the high incidence of intracranial meningiomas encountered in clinical practice, it is not uncommon to find rare subtypes of meningioma, with unusual imaging findings. These commonly represent a diagnostic challenge. In this article, we review the imaging appearance of typical meningioma on conventional and advanced imaging as well as the key imaging features of multiple uncommon subtypes: cystic, microcystic, lipomatous, chordoid, angiomatous, intraosseous, extracranial, atypical/malignant, and tumor-to-tumor metastasis (also known as collision tumors). Some of these uncommon subtypes, however, demonstrate imaging features that may allow for a more specific diagnosis, or features, which can influence patient's management.