151. Erythromelalgia

This rare condition derives its name from the Greek words erythros (redness), melos (extremity), and algos (pain). Swelling and increased skin temperature are its other cardinal features. An alternative term, erythermalgia, emphasizes the warmth and inflammation evident in the affected areas. Although erythromelalgia may appear without underlying disease, it occurs most often with a myeloproliferative disorder. Sometimes it precedes the disorder by months to years.

Symptoms frequently begin with an itching sensation followed by burning pain. Fingers, toes, or the entire limb may be affected, and involvement may be unilateral or bilateral, symmetric or asymmetric. The redness and swelling ordinarily resolve within several days, but may, as in the patient shown, last for several weeks. If left untreated, this condition may progress to dystrophic changes, painful acrocyanosis, or peripheral gangrene. Heat, standing, and exercise frequently bring on or aggravate the symptoms while resting, elevating, or cooling the involved limb gives relief.

When erythromelalgia accompanies a myeloproliferative disorder, histologic examination of affected tissue shows fibromuscular and intimal proliferation of the dermal arterioles with narrowing of their lumens. In more advanced cases, thrombi are evident. These lesions are thought to result from platelet activation and aggregation in vivo, with in situ thrombosis.

Specific treatment of these patients consists of aspirin to impair platelet aggregation combined with myelosuppressive agents designed to reduce the circulating platelet mass. Such measures in the patient shown afforded substantial clinical improvement.