Degos disease mimicking primary vasculitis of the CNS.

A 4-year-old boy developed a headache. Initial evaluation revealed a normal neurologic examination and a right subdural hygroma on CT. Worsening headaches led to hospitalization at an outside institution. MRI showed leptomeningeal enhancement; magnetic resonance angiography (MRA) was normal. Infectious, rheumatologic, hematologic, and CSF studies were unrevealing. He then developed a left-sided hemiparesis. Imaging showed increased leptomeningeal enhancement with punctate infarcts in the right hemisphere. CT angiography demonstrated irregularity involving branches of the circle of Willis suggestive of vasculitis. Methylprednisolone (30 mg·kg−1·d−1 × 5 days) was administered for presumed CNS vasculitis.