Papillary Tumor of the Pineal Region Presenting With Obstructive Hydrocephalus: A Diagnostic and Management Challenge.

We report a 45-year-old woman with a papillary tumor of the pineal region (PTPR), a neuroepithelial neoplasm of the pineal gland, who presented with a one-year history of headaches, visual disturbance, and gait impairment and was found to have a pineal mass with obstructive hydrocephalus. She underwent endoscopic third ventriculostomy (ETV) with biopsy; the initial radiologic impression favored pineocytoma. Immunohistochemistry was nondiagnostic on the limited sample, and the diagnosis of PTPR was established only after review at two academic neuropathology centers. DNA methylation profiling was obtained for definitive molecular classification, with the result not yet available for review at the time of reporting. The lesion was resected via an interhemispheric transcallosal approach, but the patient developed recurrent hydrocephalus due to ETV failure, requiring a ventriculoperitoneal shunt. She completed adjuvant radiotherapy and showed no recurrence on the most recent surveillance MRI. In this patient, PTPR posed two challenges: diagnostic overlap with pineocytoma that required specialized and molecular workup, and persistent hydrocephalus after ETV failure that ultimately required permanent cerebrospinal fluid diversion.