Gastrointestinal type 1 hypersensitivity to azathioprine.

We report the case of a 49-year-old patient with progressive sensomotor polyneuropathy who developed nausea, vomiting, and diarrhea after 2 1/2 months of azathioprine therapy. Administration of the drug was interrupted. These symptoms recurred immediately after rechallenge with azathioprine. A duodenal biopsy demonstrated a massive local eosinophilia without peripheral blood eosinophilia. Cutane testing with azathioprine showed a positive type 1 reaction. We diagnosed a hypersensitive reaction type 1 in the duodenal mucosa on the basis of the histological features, the history, and the cutane reaction.