Harlequin syndrome in a pediatric population: a case series.

Harlequin syndrome is a rare condition, presenting with unilateral facial flushing and hyperhidrosis in response to physical exercise, heat or emotional stressors and has scarcely been reported in pediatric patients. It is caused by a dysfunction of vasomotor and sudomotor sympathetic fiber activity inhibiting the ability to flush on the affected side, causing the neurologically intact side to appear red. We present three pediatric cases of this uncommon syndrome, each of them of different origin and displaying distinct associated (neurological) symptoms, and review medical literature.