Calcifying Pseudoneoplasm of the Neuraxis Presenting with Vasogenic Edema and a Perilesional Cyst.

Calcifying pseudoneoplasms of the neuraxis (CAPNONs) are uncommon benign lesions that are rarely diagnosed radiographically. We report an unusual case of a left middle cerebellar peduncle CAPNON with vasogenic edema and a perilesional cyst. The patient was a 36-year-old woman with a 20-year history of left-sided hearing loss that had recently progressed. Computed tomography and magnetic resonance imaging showed a heterogenous calcified lesion with vasogenic edema and a perilesional cyst in the left middle cerebellar peduncle. Although it is a rare radiographic feature of CAPNON, vasogenic edema should be included as a possible feature of this uncommon tumefactive lesion.