Erythromelalgia is a chronic pain disorder involving an intense burning sensation, warmth, and erythema, usually of the distal extremities, relieved by cold and exacerbated by heat. It occurs in 2 per 100,000 individuals annually and is exceedingly rarer in children. Pathogenesis is poorly understood and may have genetic, neural, and vascular involvement. 

A female infant, with history of eczema and reflux, was noted to have facial flushing at one month of age and episodic redness of the feet with fussiness at six months. At eleven months of age, she presented with episodic lower extremity erythema followed by cyanosis and irritability, triggered by heat and alleviated by cold temperatures. Milestones of reaching for objects, pulling to stand, and cruising were delayed. Her father and paternal aunt had episodic flushing and mother experienced Raynaud phenomenon.

Physical exam elicited whimpering, agitation, and erythema after submersion of the lower extremity in warm water for 1-2minutes. Symptoms abated with submerging the limb into cold water, clinically consistent with erythromelalgia. 

Low-dose oxcarbazepine was initiated which improved symptoms, allowed her to be more active, and relatively temperature tolerant. She is presently undergoing therapies and following with genetics.

Primary erythromelalgia typically appears in the first decade of life and females are predominantly affected. De novo inheritance can occur but 5% of patients have an autosomal dominantly inherited SCN9A mutation. Misdiagnosis or delayed diagnosis often occurs, given symptom fluctuation and the relatively normal extremity appearance between symptomatic periods. All ages can be affected but this case represents one of the youngest of affected patients reported with a suspicious family history. Furthermore, this case emphasizes the importance of a high level of suspicion for this rare and debilitating diagnosis.