Idiopathic granulomatous meningoencephalitis presenting as an intracranialtumor

A 2-year-old girl presented with a single episode of generalized seizure. M agnetic resonance imaging examination showed an intracranial mass with a di ameter of 2.5 cm in the right parieto-occipital region of the cerebrum. The se clinicoradiological findings were suggestive of intracranial tumor. Hist ologically, fibroblastic proliferation of storiform pattern was noted, asso ciated with epithelioid granulomas. The etiological pathogens for the granu lomas could not be detected even though investigation of special histochemi cal staining, immunohistochemical study and DNA analysis of Mycobacterium t uberculosis by polymerase chain reaction technique was performed. On electr on microscopic examination, the area appearing as a storiform pattern consi sted of fibroblasts showing much dilated rough endoplasmic reticulum and sl ender tappering cytoplasmic processes without cellular junctional complex. No organisms were identified in the granulomatous area of the lesion. From those findings the diagnosis as idiopathic granulomatous meningoencephaliti s was made.