Unveiling primary intracranial eosinophilic angiocentric fibrosis: A rare case report and diagnostic dilemmas.

Eosinophilic angiocentric fibrosis (EAF) is a rare, benign fibroinflammatory condition primarily affecting the sinonasal and upper respiratory tract, with a few cases reported beyond these regions. Primary intracranial EAF is rare. To date, only one case of intracranial EAF has been reported; ours is the second. This case report presents a case of EAF in a 55-year-old man, initially misdiagnosed as meningioma based on clinical and radiological features. The patient complained of a persistent dull headache for six months without associated neurological symptoms. Brain magnetic resonance imaging revealed a dural-based lesion with characteristics suggestive of meningioma. However, histopathological examination post-surgical resection revealed a nodular vascular lesion with concentric angiocentric fibrosis, a distinctive onion skin pattern, and an inflammatory infiltrate rich in eosinophils, plasma cells, and histiocytes. Immunohistochemistry ruled out IgG4-related disease, and other systemic disorders were ruled out based on combined clinical and histological features. This case underscores the need for considering EAF in the differential diagnosis of dural-based lesions. Awareness of its potential mimicking of meningioma is crucial for accurate diagnosis and appropriate management, emphasizing the importance of histopathological examination in challenging cases.