Histopathologic findings in primary erythromelalgia are nonspecific: special studies show a decrease in small nerve fiber density.

The histopathology of primary erythromelalgia has been poorly characterized. A total of 33 skin biopsy specimens from 29 patients with a diagnosis of primary erythromelalgia were re-examined. Histopathologic findings were nonspecific. Vascular thrombi were not identified. A relative decrease in small nerve fiber density was noted in specimens from 13 of 16 patients.