Typical, atypical, and misleading features in meningioma.

TLDR

Meningiomas are the most common primary CNS tumors, usually benign with characteristic imaging, yet histologic variants and atypical radiologic presentations can be misleading. The study aims to alert radiologists to uncommon and misleading imaging features of meningioma to improve diagnostic accuracy.

Abstract

Meningiomas are the most common nonglial primary tumors of the central nervous system and the most common extraaxial neoplasms, accounting for approximately 15% of all intracranial tumors. They are usually benign neoplasms, with characteristic pathologic and imaging features. However, there are several important histologic variants of meningioma, and even a histologically typical meningioma can have unusual or misleading radiologic features that may not be suggestive of meningioma. The typical meningioma is a homogeneous, hemispheric, markedly enhancing extraaxial mass located over the cerebral convexity, in the parasagittal region, or arising from the sphenoid wing. Meningiomas may originate in unexpected locations such as the orbit, paranasal sinus, or ventricles or be entirely intraosseous (within the calvaria). Unusual imaging features such as large meningeal cysts, ring enhancement, and various metaplastic changes (including fatty transformation) can be particularly misleading. Because meningiomas are so common, the radiologist must be aware of their less frequent and uncharacteristic imaging features in order to suggest the correct diagnosis in cases that are atypical.