Pineocytoma is a rare tumor. It is rare for pineocytoma to present as leptomeningeal metastasis. We present a rare case of pineocytoma with malignant transformation and leptomeningeal metastasis after subtotal tumor resection and adjuvant radiotherapy. This case was a 58-year-old male with an unsteady gait for 2 months. Enhanced brain magnetic resonance imaging revealed a heterogeneous mass involving the pineal region. The initial pathological diagnosis of pineocytoma was confirmed after subtotal tumor resection. Two years after adjuvant radiotherapy to the primary site, the magnetic resonance imaging showed C2 and T2 metastatic lesions, with the final pathological diagnosis being pineal parenchymal tumor (PPT) with intermediate differentiation after the removal of T2 intramedullary tumor. After that adjuvant radiotherapy at the cervical and thoracic spinal cord was completed. There was no recurrence of the tumor 1 year after the radiotherapy. We report a rare case of pineocytoma with malignant transformation to PPT with intermediate differentiation and leptomeningeal dissemination.
Keywords: Leptomeningeal dissemination; malignant transformation; pineal parenchymal tumor with intermediate differentiation; pineocytoma; radiotherapy.