Optic nerve perineuritis and retroperitoneal panniculitis: rare first presentations of Behcet's disease.

A 46-year-old woman was admitted to our hospital because of high fever and lumbago. CT revealed increase in density of fat tissue around the aorta, suggesting retroperitoneal panniculitis. The following day, she reported of leg pain, pain in the mouth, painful urination and right eye pain that was exacerbated by eye movement. We observed erythema nodosum, aphthous stomatitis and genital ulceration. Ophthalmologic examination revealed mild right optic disc oedema. Visual acuity was normal in both eyes. MRI with gadolinium infusion revealed enhancement around the right optic nerve, suggesting optic nerve perineuritis (ONP). A diagnosis of Behcet's disease was made. She was treated with prednisolone and colchicine with a favourable response. A warning sign of ONP is eye pain that is exacerbated by eye movement. MRI with gadolinium infusion should be performed immediately in such cases to prevent vision-threatening sequelae.