Occurrence of granulomatous appendicitis in rabbits

Abstract

Granulomatous appendicitis was observed in all of the 45 Japanese white rabbits examined. Histologically, multiple microgranulomas were accompanied with foreign body giant cells and focal calcifications in lymph nodules of appendix. Foreign body giant cells contained hair coat and larvae of Passalurus ambiguus. In addition, the sacculus rotundus and mesenteric lymph nodes were affected with the same lesions. PAS- and Gram- positive bacilli were phagocytized in the microgranulomas and macrophages. They were also stained positively with the immunoperoxidase method for the auto-sera of rabbits. Isolation of these bacilli in pure culture has not yet been accomplished. The occurrence of granulomatous lesions due to tuberculosis, pseudotuberculosis, tularemia and actinomycosis seems unlikely in the present cases because none of these organisms nor characteristic lesions were detected. It was suggested that the Gram-positive bacilli appeared to play a role in granulomatous appendicitis.