24 Angiomatous Meningioma: A Rare Mimicker of Vascular Central Nervous System Neoplasms

Introduction/Objective Angiomatous meningioma is an uncommon histological variant of meningioma, accounting for approximately 2.1% of all cases. This subtype is characterized by an abundance of small and large vascular channels, which may predominate over the meningothelial elements, potentially leading to diagnostic confusion with other vascular CNS neoplasms, such as hemangioblastoma and hemangiopericytoma. Its highly vascular nature poses challenges during frozen section evaluation, as it can be misinterpreted as other aggressive lesions or lead to diagnostic uncertainty due to tissue distortion and scant tissue samples. Methods/Case Report We present the case of a 57-year-old female with no prior neurological symptoms who presented with a first-time seizure. Brain MRI revealed an avidly enhancing 3.6 cm dural-based mass in the right frontoparietal region with significant perilesional edema and mild mass effect. An additional 0.8 cm extra-axial lesion was identified in the left frontotemporal region. The primary differential diagnosis included meningioma, though a dural-based metastasis was also considered. Given the patient’s clinical presentation and imaging findings, she underwent craniectomy and gross total resection of the larger mass. Frozen section evaluation was performed intraoperatively, but interpretation was limited due to the tumor’s vascular nature. The frozen section slides primarily showed abundant vascular spaces, raising concerns for a vascular neoplasm, however an angiomatous meningioma could not be excluded. Due to these challenges, a definitive diagnosis was deferred to permanent sections. Histopathological analysis of resected tumor demonstrated prominent microcystic and angiomatous morphology with numerous dilated vascular channels interspersed within a meningothelial framework. The mitotic activity was low, with no evidence of atypical features or brain invasion. Based on these findings, a final diagnosis of meningioma, microcystic and angiomatous subtypes, CNS WHO Grade 1, was rendered. Postoperative imaging showed expected postsurgical changes, including a small volume of pneumocephalus, subdural and subarachnoid hemorrhage at the resection bed, and residual vasogenic edema. Importantly, there was no evidence of downward herniation or new mass effect. The patient demonstrated steady neurological improvement at follow-up. Results NA Conclusion This case highlights the critical role of histopathology in accurately diagnosing angiomatous meningioma, a rare yet distinct entity that can closely resemble other vascular CNS tumors like hemangioblastoma and hemangiopericytoma. However, its highly vascular nature makes frozen section evaluation particularly challenging, as it can mimic more aggressive neoplasms and be complicated by tissue distortion. Recognizing this rare variant is essential for pathologists, radiologists, and neurosurgeons to prevent misdiagnosis and ensure optimal patient outcomes.