Chiasmal haemorrhage secondary to glioma with unusual MRI appearance.

OBJECTIVE To report a unique case of haemorrhagic presentation of a chiasmal and optic tract glioma (OPG) appearing as an extra-axial lesion on MRI scans. CASE REPORT A 30-year-old female with a preoperative radiological diagnosis of dermoid cyst was operated. No lesion was found in the chiasmal or carotid cisterns within the operative field. The right posterolateral corner of the chiasma and the beginning of the right optic tract appeared swollen. The area was incised and a haemorrhagic fluid poured through the opening. Several samples were taken and the pathological diagnosis was of pilocytic glioma. CONCLUSIONS We present a unique case of chiasmal bleeding into the optic pathway secondary to an optic glioma which radiologically mimicked an intracisternal cyst. In similar cases, rapid clinical evolution of the symptoms may be vital for the differential diagnosis. Surgery is warranted to prevent permanent damage to the visual pathway.