Magnetic resonance imaging findings of intracranial papillary meningioma: a study on eight cases.

OBJECTIVES: To increase the awareness on intracranial papillary meningiomas (PMs) by presenting magnetic resonance imaging (MRI) findings on this disease. MATERIALS AND METHODS: The MRI findings and clinical presentations of nine discrete lesions in eight patients with pathologically documented PMs were retrospectively analyzed. RESULTS: Most tumors occurred in young adults. The tumors originated from the convexity meninges in five cases and from the parasagittal regions in four cases. The tumor shape was irregular in six cases, lobulated in two cases, and round in one case. By MRI, nine masses were primarily isointense (n=5) or mildly hypointense (n=4) to gray matter on T1-weighted images and inhomogeneous hyperintense (n=3) or isointense (n=6) to the cortex on T2-weighted and fluid-attenuated inversion recovery images. On diffusion-weighted imaging, the signal intensity of the tumor was increased in all lesions compared with the adjacent parenchyma. Tumor and brain interfaces were unclear in seven cases, cyst formation was observed in eight tumors, scattered hemorrhage was observed in three tumors, signal voids due to vessels were visible in four cases, and eight tumors had moderate or marked irregular peritumoral edema. Enhancement was homogeneous (n=2) or heterogeneous (n=7), an area of focal nodular enhancement was observed in three lesions, and the dural tail sign was visible in seven cases. CONCLUSION: Although PM is rare, it should be considered in the differential diagnosis when evaluating intracranial neoplasms. Younger patient age, as well as imaging features such as unclear tumor-brain interface, internal heterogeneity including cyst formation, irregular enhancement, signal voids of vessels, and marked peritumoral edema can help distinguish PM from typical benign meningiomas.