A pediatric case of idiopathic Harlequin syndrome.

Harlequin syndrome, which is a rare disorder caused by dysfunction of the autonomic system, manifests as asymmetric facial flushing and sweating in response to heat, exercise, or emotional factors. The syndrome may be primary (idiopathic) with a benign course, or can occur secondary to structural abnormalities or iatrogenic factors. The precise mechanism underlying idiopathic harlequin syndrome remains unclear. Here, we describe a case of a 6-year-old boy who reported left hemifacial flushing and sweating after exercise. He had an unremarkable birth history and no significant medical history. Complete ophthalmological and neurological examinations were performed, and no other abnormalities were identified. Magnetic resonance imaging was performed to exclude lesions of the cerebrum and cervicothoracic spinal cord, and no abnormalities were noted. His final diagnosis was classic idiopathic harlequin syndrome. Herein, we report the first pediatric case of idiopathic harlequin syndrome in Korea.