Acrodynia

1 - CLINICAL REMINDER

The patients who present with a clinical picture of acrodynia are essentially paediatric patients and the condition has predominantly been reported in young children and infants chronically exposed to mercury or following a viral infection. The hands and feet are cold, more or less erythematous and extremely painful, which sometimes even leads to self-injury. Neurological signs including confusion and limb weakness are generally the first signs of intoxication. Oedema and lesions affecting the extremities then appear progressively. When neuropathy is severe, accompanied by consciousness disorders, the child mechanically keeps rubbing his/her feet on one another. This specific clinical picture may sometimes be associated with other manifestations such as diarrhoea and chronic stomatitis. Tachycardia and high blood pressure may also be observed and patients should be tested for mercury poisoning if they present with acrodynia-type lesions of the extremities. More diffuse cutaneous lesions such as desquamation and erythroderma have also been observed, sometimes accompanied by significant pruritus.

The lesions observed on the hands and the feet of children are sufficiently suggestive for a diagnosis of mercury poisoning to be considered and the condition should be treated rapidly if the diagnosis is confirmed. However, erythema is not observed consistently and acroparesthesia, often triggered by heat, and even real acrodynic syndromes have been observed with Fabry’s disease, a form of hereditary sphingolipidosis linked to a mutation on the X-chromosome that occurs in young, male patients, even before the appearance of angiokeratomas in the underpants area. With more pronounced erythema, the differential diagnosis should include erythermalgia, which occurs predominantly in the feet and is characterized by erythema and intense pain often triggered by heat and relieved by exposure to cold or, to a lesser degree, by raising the affected limb. The specificity of erythermalgia, unlike acrodynia, is that the condition progresses in painful, paroxysmal attacks and the extremities are normal between attacks. Furthermore, the condition is not associated with any particular neurologic manifestations.