An uncommon presentation of stroke in a child with trisomy 21.

A 3-year-old boy was presented to the emergency department with fever and refused to bear weight on his left leg. Evaluation leads to the eventual diagnosis of stroke secondary to moyamoya syndrome. This is an unusual presentation of stroke and highlights the need to expand the differential diagnosis of common presentations to include rare diseases in children with predisposing conditions. We explore the relationship between trisomy 21 and moyamoya syndrome and then briefly discuss strokes in childhood.