[False erythermalgia].

The differential diagnosis of erythermalgia is sometimes complicated by the absence of consensus on proposed diagnostic criteria. Unwarranted diagnosis can result from any clinical situation leading to burning sensations in the limbs. This can occurs in patients with peripheral neuropathies who often experience dysesthesia when going to bed when the legs are under the covers; in such cases, redness and local warmth are missing. Venous insufficiency can also produce sensations of warm feet, often at retiring, together with edema and an increase in local heat. Algodystrophy, during the inflammatory phase can also mimic erythermalgia with intense pain and local modifications. Nevertheless, the unilateral aspect and persistence of the symptoms together with the post-traumatic situation usually directs the diagnosis. Acrodynia is a rare disease caused by excessive mercury intake and should be discussed in children. Vasomotor impairment in the limbs is the main sign. The red color of the hands and feet is accompanied by intense paroxysmal burn-type pain. The diagnosis is confirmed by high mercury levels in urine. Fabry's disease is a hereditary sphingolipidosis transmitted on chromosome X and occurs predominantly in men, often starting early in childhood with burning sensation in the limbs. The diagnosis should be entertained in children with pseudo-erythermalgia and is confirmed by chromatographic search for abnormal sphingolipids in the urine.