Papillary glioneuronal tumour: a report of a rare case and review of literature.

INTRODUCTION: Amongst the mixed glioneuronal tumours, 'papillary glioneuronal tumour', a new variant, has been described recently. CASE REPORT: We report a case of papillary glioneuronal tumour in a 4-year-old boy who presented with fever, weakness of left upper and lower limbs and headache for the last 2.5 month. Radiologic examination showed a cystic space-occupying lesion with mural nodule in the right frontal lobe with extension into white matter. Surgical excision of a large cystic mass with small solid nodule was done. Pathological examination revealed a well-circumscribed tumour showing predominantly papillary architecture with focal aggregates of cells in sheets. The papillae were composed of hyalinised blood vessels lined by single to multi-layered cells. The tumour cells showed mild pleomorphism without any necrosis. The individual tumour cells had scant eosinophilic cytoplasm, round to oval hyperchromatic nucleus with occasional mitoses. The tumour cells were immunopositive for glial fibrillary acidic protein, synaptophysin, vimentin, and S-100 protein, but negative for neurofilament, epithelial membrane antigen, cytokeratin and CD34. MIB-1 labelling index was approximately 12% in the highest proliferating areas. In view of subtotal excision of the tumour and high MIB-1 labelling index (LI), the patient was given chemotherapy and he is doing well at 1-year follow-up. DISCUSSION: This report supports the existence of this rare tumour. Some of its rare clinicopathological features like young age, cyst with mural nodule, presence of mitoses and raised MIB-1 LI need to be documented.