What is the pathophysiology of erythema dyschromicum perstans (EDP)?

Updated: Apr 19, 2019
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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The etiology of erythema dyschromicum perstans is unknown, but many consider erythema dyschromicum perstans to be a variant of lichen planus actinicus. A variety of predisposing factors have been cited. These include ingestion of ammonium nitrite, an intestinal parasitosis caused by nematodes (whipworm infection, control of which produced erythema dyschromicum perstans remission), orally administered radiographic contrast media, and, possibly, an occupationally associated cobalt allergy in a plumber. One case may be particularly revealing, that of a 13-year-old rural northern European truant who repeatedly ingested small amounts of a fertilizer, ammonium nitrate, to induce erythema dyschromicum perstans and avoid school. Chlorothalonil exposure among banana farm workers is another possible cause of erythema dyschromicum perstans. [8]

An abnormality in cell-mediated immunity might play a role. However, substantial immune dysfunction is limited at present to 1 report of an HIV-seropositive 41-year-old homosexual of Chinese lineage with erythema dyschromicum perstans. [9, 10]

HLA-DR association with the genetic susceptibility to develop ashy dermatosis in Mexican Mestizo patients was analyzed, the results of which were reported by Correa in 2007. [11] The most frequent allele was HLA-DR4 (65%), compared with 23% in controls. These Mexican patients had HLA-DR4 subtype *0407, which is also found in the Amerindian population. [12, 13] Thus, although many factors may be involved, an important genetic susceptibility appears to be conferred by genes located within the major histocompatibility complex region.

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