Meningeal Hemangiopericytoma Presenting as Pure Gerstmann Syndrome: A Double Rarity.

Gerstmann syndrome is a neurobehavioral syndrome characterized by four cardinal symptoms: acalculia, agraphia, finger-toe agnosia, and dysgraphia. The syndrome is caused primarily by lesions at the confluence of parietal, temporal, and occipital lobes, but also can involve the middle frontal lobe of the dominant hemisphere. Documented inciting lesions include stroke, tumor, hemorrhage, arteriovenous malformations, and seizures. A meningeal solitary fibrous tumor (SFT)/hemangiopericytoma (HPC) is a diagnostic challenge due to its resemblance to more common brain tumors like meningioma, with histopathology being the definitive diagnostic test. A 37-year-old male presented to our tertiary center with blurred vision, "not being himself," and "acting funny" for three weeks. On exam, he was found to have a right inferior quadrantanopia, grade II papilledema and demonstrated all four symptoms of Gerstmann syndrome - inability to perform simple calculations (acalculia), or identify his fingers (finger agnosia), could not distinguish his left side from the right (left-right disorientation), nor write out his name (agraphia). Brain imaging showed an extra-axial, highly vascularized 7.6-cm mass compressing the left parietal lobe. He underwent a complete resection of the mass. Postoperatively, he had gradual improvement with complete resolution of agraphia, acalculia, finger agnosia, and left-right disorientation within a week status post-resection. Tumor pathology indicated hemangiopericytoma/solitary fibrous tumor. This case enunciates the enigmatic tetrad of Gerstmann syndrome. Though classically described as a sequela of stroke, the mass effect of the tumor on the parietal lobe may produce the symptoms, which can resolve following resection.