Atypical Growth Pattern of an Intraparenchymal Meningioma.

Meningiomas are the most common primary nonneuroglial extra-axial neoplasms, which commonly present as spherical or oval masses with a dural attachment. Meningiomas without dural attachment are rare and, according to their locations, are classified into 5 varieties, including intraventricular, deep Sylvain fissure, pineal region, intraparenchymal, or subcortical meningiomas. To the best of our knowledge, intraparenchymal meningioma with cerebriform pattern has never been reported. In this paper, we report a 34-year-old Chinese male patient who presented with paroxysmal headaches and progressive loss of vision for 10 months and blindness for 2 weeks. A thorough physical examination revealed loss of bilateral direct and indirect light reflex. No other relevant medical history and neurologic deficits were noted. Computed tomography and magnetic resonance imaging scans showed an irregular mass with a unique cerebriform pattern and extensive peritumoral edema in the parietal-occipital-temporal region of the right cerebral hemisphere. The initial diagnosis was lymphoma. Intraoperatively, the tumor was completely buried in a sulcus in the parietal-occipital-temporal region without connecting to the dura. The histological diagnosis was intracranial meningioma based on pathological examination. Therefore, when an unusual cerebriform growth pattern of a tumor is encountered, an intraparenchymal meningioma should be considered as a differential diagnosis.