Fibrin ring granulomas and allopurinol.

To test the hypothesis that allopurinol-associated granulomatous hepatitis may present itself with fibrin-ring granulomas, we requested details of such cases, as reported to the World Health Organization, from 13 national adverse reaction monitoring centers, and as reported in the literature. Details and histology of 6 cases were obtained and reviewed. All consisted of acute hypersensitivity signs with fever, rash, arthralgia, or eosinophilia as hallmarks, starting within 6 wk of commencing treatment with allopurinol. In all cases there were either epithelioid granulomas or granulomalike lesions, but none of these contained fibrin rings. It is concluded that, if fibrin-ring granulomas are a manifestation of allopurinol-induced granulomatous hepatitis, this feature is probably uncommon.