[Inconsolable crying revealing primary erythermalgia in a 6-month-old infant]

Erythermalgia is a peripheral vascular disease triggered by exposure to heat. The primary infantile form is rare. No cases have been described in infants. We report a case in a 6-month-old child revealed by crying bouts associated with erythema of the lower limbs. A 6-month-old child was brought in for consultation for daily crying bouts, occurring six times a day, associated with erythema of the lower limbs. Blood count, abdominal ultrasound and endoscopy were normal, excluding gastroesophageal reflux and intussusception. Attacks disappeared during winter but recurred at high temperatures. The diagnosis was primary infant erythemalgia. Treatment with analgesics and ice packs was established. Erythermalgia is a rare peripheral vascular disease characterized by paroxysmal pain triggered by heat and relieved by cold. The primary form occurs in childhood but has never been reported in infants. The pathophysiology is based on an alteration of sodium channels inducing neuropathy in small-caliber fibers. Genetic mutations have been found in the SNC9 gene on chromosome 2q, with autosomal dominant transmission. Support of this condition is difficult due to resistance to conventional analgesics. The prognosis is sometimes poor with a significant death rate in the pediatric population.