Erythromelalgia: review of clinical characteristics and pathophysiology.

Erythromelalgia is characterized by burning discomfort, warmth, and dermal erythema of the feet and/or the hands. Lowering the involved part and exposure to heat worsen symptoms, whereas elevation or cooling of the extremity relieves the discomfort. Several different subtypes of erythromelalgia have been documented and include an adult-onset form secondary to myeloproliferative syndrome-related thrombocytosis and an early-onset form that appears in childhood or adolescence and is idiopathic. A disturbed platelet function affecting the microvasculature has been implicated in thrombocythemia-related erythromelalgia. Importantly, manifestations of erythromelalgia often precede the onset of the myeloproliferative disease by several years. Therefore, the blood cell count should be monitored periodically in all adult patients with erythromelalgia. An abnormal hemoglobin, white blood cell, or platelet count or the presence of immature cells in the differential should prompt the physician to initiate a diagnostic evaluation for an underlying hematologic disorder. The symptoms of adults with erythromelalgia are markedly relieved after treatment with a single daily dose of acetylsalicylic acid. In contrast, childhood erythromelalgia appears without an underlying disorder, may be familial, and is resistant to treatment with aspirin.