Papillary Glioneuronal Tumor of the Left Parieto-Occipital Lobe Presenting with Diplopia in an 11-Year-Old Girl

Papillary Glioneuronal Tumor (PGNT) is a rare mixed glioneuronal neoplasm classified as CNS WHO grade 1 and is most often reported in young adults. Pediatric cases, particularly in the parieto-occipital region with predominant visual symptoms, are uncommon. We reported on an 11-year-old girl who presented with headache, right periorbital pain and diplopia for 10 days. Examination revealed restriction of the right temporal visual field, uncrossed diplopia in upward gaze and right lateral rectus paresis. Preoperative MRI demonstrated a large left parieto-occipital solid-cystic intra-axial lesion with an enhancing solid component and associated mass effect. The patient underwent left parieto-occipital craniotomy and excision of the lesion in lateral position with head fixation in a Sugita clamp. A single burr-hole-based parieto-occipital craniotomy was performed. Intraoperatively, a solid-cystic tumor was noted; the solid component was greyish, firm to hard, not suckable and moderately vascular, while the cystic component contained yellowish fluid. Gross total excision was achieved. Cytology of the cyst fluid showed cerebral cyst fluid with no abnormal cells. Histopathology revealed a heterogeneous tumor with papillary structures having fibrocollagenous cores and a single to pseudostratified lining. A biphasic pattern of glial and neuronal components was seen with stromal hyalinization and calcification. Immunohistochemistry showed GFAP and S100 positivity in papillary lining cells and synaptophysin positivity in cells with neuronal morphology; p53 expression was absent. MIB-1 labeling index reached approximately 10% in areas with highest expression. The final diagnosis was papillary glioneuronal tumor (CNS WHO grade 1). Postoperatively, the patient was stable and diplopia resolved. A routine postoperative MRI on day 12 showed a heterogeneously enhancing residual-appearing lesion in the left high parietal/parasagittal parieto-occipital region. In view of residual disease, adjuvant radiotherapy was advised. This case adds to the limited pediatric literature on PGNT and highlights an unusual parieto-occipital presentation with diplopia and visual field deficit.