Red skin re-read

Although relatively rare, the symptom complex of intermittent acral warmth, pain, and erythema that defines erythromelalgia (EM) has been well documented in the medical literature for over 150 years (Graves, 1838). Despite an extended awareness of this phenomenon, the cause and underlying mechanisms have until recently been completely obscure. Part of the difficulty in understanding EM has been the heterogeneity of the affected population. EM is often idiopathic or `primary,' but also has been reported to be associated with myleoproliferative and hemotologic disease, autonomicnervous system disease, pharmacologic agents, viral infections and pregnancy. It is not clear what common pathologic features in these settings produce the EM symptom complex. EM is also rare, with an estimated incidence of approximately 3 per million in the. Norwegian population (Kvernebo, 1998). Hence, there are few centers that follow a large enough population of patients to perform studies that are large enough to identify consistent physiologic features. Furthermore, as suggested by Mark et al in this issue of the JID, as well as by other authors, the underlying pathologic mechanisms are likely to involve a complex dysregulation of cutaneous blood flow that ultimately results in microvascular ischemia. Determining the nature of this dysfunction has also been challenging because the control of cutaneous blood flow is dependent on an interplay of systemic and local signals, and is not completely understood.