Idiopathic harlequin syndrome: a pediatric case.

Harlequin syndrome, Harlequin sign, Holmes-Adie syndrome, and Ross syndrome lie on a spectrum of partial dysautonomias affecting facial sudomotor, vasomotor, and pupillary responses. These syndromes have imprecise clinical boundaries and overlap syndromes are known. We report a 9-year-old girl who presented with anhidrosis over the right half of her face and the left side of her body, with compensatory hyperhidrosis on the contralateral side. She was noted to have bilateral tonic pupils and normal muscle stretch reflexes with other features suggestive of autonomic dysfunction. Investigations to rule out secondary causes were noncontributory. Her clinical presentation can be categorized as partial overlap between Harlequin syndrome and Holmes-Adie syndrome.