Ingestion of ammonium nitrate as a possible cause of erythema dyschromicum perstans (ashy dermatosis).

Clinically and histologically typical erythema dyschromicum perstans has been provoked by repeated ingestion of very small amounts of a fertilizer, ammonium nitrate. It has been used by a boy who has noticed accidentally that after licking the fertilizer he developed hyperpigmentations. His main purpose was to avoid school attendance, and he developed a very ingenious method of licking the fertilizer once in several weeks in such a way that it did not produce any digestive or other troubles. His brother, an uniovular twin who had no contact with ammonium nitrate, was healthy. The case supports Pinkus' hypothesis that this type of lesions may be related to some environmental contaminant. Attention is called to a possible food contamination by ammonium nitrate.