Melanomatous Leptomeningeal Carcinomatosis masquerading as Guillain-Barré Syndrome.

A 49 year old man presented with rapid onset paraparesis, evidence of lower motor neurone features and sensory impairment following a respiratory tract infection. Initially he was treated with intravenous immunoglobulins for suspected Guillain-Barré syndrome (GBS). Subsequent cerebrospinal fluid (CSF) analysis identified unexpectedly high protein levels (attributable to Froin's syndrome1) and magnetic resonance imaging (MRI) was highly suggestive of leptomeningeal carcinomatosis and cerebral metastases secondary to disseminated malignant melanoma. The disease progressed with rapid deterioration despite high dose corticosteroids and the patient died 12 days after admission. This case brings several key points to the attention of the acute physician, in particular the need to give serious consideration to the differential diagnosis of cancer in a patient presenting with lower limb weakness.