Thrombocythemic erythromelalgia, primary erythermalgia, and secondary erythermalgia: three distinct clinicopathologic entities.

On the basis of clinical, laboratory, and histopathologic studies, the authors discern three distinct types of red, congested, and burning extremities that need to be distinguished for effective treatment according to their etiology: erythromelalgia in thrombocythemia, primary erythermalgia, and secondary erythermalgia. Each entry is discussed in turn.