[Erythromelalgia: a familial case. Discussion on the role of mercury].

Erythromelalgia is an acrosyndrome characterized by paroxysmal manifestations associating erythema, local sensations of warmth and pain which improve with exposure to cold. Childhood forms, exceptional and usually primary, are quite severe and particularly resistant to treatment. The search for a causal agent is most often negative and the pathogenesis remains to be determined. We report a case of erythromelalgia observed in a 4-year-old girl, her father and her younger sister. This case was particular due to an association with mercury poisoning. The symptomatology was improved after different therapeutic attempts including Clomipramide and, particularly effective, rerigerating socks (D(r) Comet, CNES, Toulouse). In the literature we were unable to find any case of erythromelalgia related to mercury poisoning. The cases of familial erythromelalgia reported suggest X-linked dominant transmission. Finally, this case demonstrated the difficulties in diagnosing and treating erythromelalgia, especially in the child.