Granulomatous Appendicitis
Granulomatous appendicitis is a rare condition accounting for less than 2% of all cases of appendicitis (1). Crohn's disease, once thought to account for most cases, appears to be the cause in only 5-10% of cases. A diverse group of etiologies including infection by mycobacteria, fungi or parasites, foreign body reaction and sarcoidosis account for less than 10% of cases. Infection with pathogenic Yersinia species has been demonstrated in approximately 25% of cases (2). The remaining  cases (the majority) appear to be related to subacute/recurrent appendicitis treated with interval (delayed) appendectomy. Granulomatous appendicitis has been reported to be present in as many as 59% of interval appendectomy specimens (3).

1- Bronner MP. Granulomatous appendicitis and the appendix in idiopathic inflammatory bowel disease. Semin Diag Pathol 2004; 21:98-107.
2- Lamps LW et al. The role of Yersinia enterocolitica and Yersinia pseudotuberculosis in granulomatous appendicitis: a histologic and molecular study. Am J Surg Pathol 2001; 25:508-515.
3- Guo G, Greenson JK. Histopathology in interval (delayed) appendectomy specimens: strong association with granulomatous and xanthogranulomatous appendicitis. Am J Surg Pathol 2003; 27:1147-51.
Microscopic Images of Granulomatous Appendicitis