Incidental multifocal calcifying pseudoneoplasm of the neuraxis: case report and literature review.

Calcifying pseudoneoplasm of the neuraxis (CAPNON) is thought to be a rare tumefactive lesion with unknown pathogenesis. Its prevalence is questionable with few previously reported cases of incidental CAPNON, and likely underdiagnosis. We report a unique case of incidental multifocal CAPNON. A 64-year-old female was admitted with loss of consciousness due to a ruptured right middle cerebral artery aneurysm with subarachnoid and intraventricular hemorrhage. She has a craniotomy and clipping. At time of operation, numerous small dural-based nodules were found, and one was excised for biopsy and was diagnosed as CAPNON. Retrospective review of her CT images identified nodules that were all ipsilateral to the ruptured aneurysm. A literature review revealed that incidental and/or multifocal CAPNONs are rare but likely underreported. Our case suggests a reactive process in the pathogenesis of CAPNON.