Eosinophilic fasciitis associated with use of L-tryptophan: a case-control study and comparison of clinical and histopathologic features.

We investigated the relationship between use of L-tryptophan and development of eosinophilic fasciitis by two methods: a retrospective patient survey and a case-control study of patients with eosinophilic fasciitis diagnosed at the Mayo Clinic between 1977 and 1989. Before 1986, no traceable patients with eosinophilic fasciitis had taken L-tryptophan. Between Jan. 1, 1986, and July 31, 1989, 8 of 34 patients had ingested L-tryptophan (P less than 0.001). In the case-control study, traceable patients with eosinophilic fasciitis were matched with patients who had systemic sclerosis or rheumatoid arthritis and healthy control subjects who had undergone a general medical examination. Of the 60 matched control subjects, 2 had used L-tryptophan. Thus, the odds ratio was 19, indicating a 19-fold greater likelihood of use of L-tryptophan in patients with eosinophilic fasciitis than in the control group. A retrospective assessment of clinical features, response to treatment, and blinded review of biopsy specimens of skin and fascia in patients who had eosinophilic fasciitis with or without exposure to L-tryptophan disclosed no significant differences in the two groups. This retrospective study confirms a strong association between consumption of L-tryptophan and development of eosinophilic fasciitis in some patients. No clinical or histopathologic features were detected that distinguished this disorder on the basis of previous exposure to L-tryptophan.