Idiopathic unilateral circumscribed hyperhidrosis is an extremely rare form
of increased sweat production that occurs within a sharply demarcated area
on the face or upper extremities of otherwise healthy patients. There are
no associated neurovascular or metabolic abnormalities, We report idiopathi
c localized unilateral hyperhidrosis on the upper extremity of a healthy 4-
year-old girl.