Primary sinonasal undifferentiated carcinoma presenting with bilateral retrobulbar optic neuropathy.

A 43-year-old man presented with acute bilateral visual loss. Ophthalmologic examination revealed no light perception in the right eye and a visual acuity of 20/50 in the left eye with a right afferent pupillary defect. Ophthalmoscopic examination was normal. Brain MRI showed an intracranial but extra-axial mass in the floor of the anterior cranial fossa extending along the olfactory groove and into the sinonasal vault. Endoscopic biopsy showed a high-grade neoplasm consistent with sinonasal undifferentiated carcinoma. This case report highlights an unusual clinical presentation for this rare and aggressive neoplasm.