Giant Thrombosed Middle Meningeal Artery Aneurysm Mimicking a Meningioma.

INTRODUCTION: True middle meningeal artery aneurysms (MMAAs) are extremely rare, with fewer than 20 documented cases and only one previously described as a giant aneurysm in a patient with fibrous dysplasia. Typically measuring under 10 mm, these lesions can be mistaken for other vascular abnormalities such as intracranial aneurysms, arteriovenous malformations (AVMs), or dural arteriovenous fistulas (DAVFs). This report describes a unique vascular lesion combining four rare features: (1) true MMAA, (2) giant in size, (3) completely thrombosed, and (4) mimicking a tumor (pseudotumoral behavior).

MATERIAL AND METHODS: A 70-year-old male with no history of cranial trauma presented with right hemiparesis following a seizure. Imaging revealed a 266cc extra-axial mass in the left fronto-parieto-temporal region, causing significant midline shift (18 mm) and ventricular compression. CT and MRI findings showed a well-circumscribed lesion with post-contrast enhancement and a dural tail sign, raising suspicion for a meningioma. Surgical resection was performed using standard meningioma techniques. During microsurgical dissection and debulking, intraoperative pathology revealed non-neoplastic tissue.

CONCLUSION: This case highlights the potential for true MMAAs to mimic other intracranial pathologies. Due to their location and dural involvement, a high index of suspicion is essential. We recommend specific preoperative and intraoperative considerations for surgeons encountering similar presentations to avoid misdiagnosis and guide appropriate management. These include invasive imaging techniques, acceptable subtotal resection of the lesion given the lack of regrowth possibilities and optimal dural reconstruction to avoid complications such as cerebrospinal fluid fistulae.