Abstract: Abstract: Primary erythermalgia is a rare clinical syndrome characterized by intermittent elevated skin temperature, acrodynia, inflamed and swelling and burning pain in skin of bilateral limb. For clinical and genetic studies of primary erythermalgia, only a few cases were reported in China. This study retrospectively analyzed the clinical characteristics and genetic phenotypes of a child with primary erythermalgia diagnosed by genetics. The boy was firstly showed his symptom as acrodynia when he was 8 years old. The pain was related with temperature. The affected skin was inflamed and skin temperature was elevated. At the age of 10, the acrodynia was aggravated, and the child was admitted to our hospital one year later. A heterozygous c.2566G>C (p.G856R) mutation was identified in SCN9A gene, which was not found in both parents. The clinical symptoms and genetic characteristics of the child were in line with primary erythermalgia. It was relieved after lumbar sympathetic block treatment. When acrodynia in children and adolescents especially related to temperature changes, accompanied by the inflamed and swelling limb, the possibility of primary erythermalgia should be considered. SCN9A gene analysis is helpful for diagnosis.

Key words: erythromelalgia, pain, child, case reports, SCN9A gene