Central neurocytoma is a rare primary brain tumour, mostly localised in the lateral ventricles in relation to the foramen of Monro.To report a case of a rare central neurocytoma with a complete loss of Synaptophysin expression and provide the differential diagnosis.We describe a case of a 34-year old man with a headache, unsteady gait and dim vision. MRI demonstrated a tumorous expansion localised in both lateral ventricles. The patient underwent a subtotal resection. Histology showed a picture consistent with central neurocytoma, but tumour was completely negative for Synaptophysin. We describe our approach in such a diagnostically difficult case.In the rare case of Synaptophysin-negative central neurocytoma, its neuronal differentiation should be substantiated by electron-microscopic examination. Unfortunately in the routine work, biopsy samples are usually fixed in formalin fixative which does not preserve ultrastructure well. In such situations, an accurate diagnosis is disputable and based on careful assessment of the histological features, exclusion of tumours with similar morphology and detailed correlation with MRI pictures (Fig. 4, Ref. 6). Full Text (Free, PDF) www.bmj.sk.