LAUSR

INTRODUCTION Granulomas are a pathologic hallmark of Crohn's disease (CD) although they are found in only a subset of patients. Well-formed granulomas are associated with an aggressive phenotype although it is unknown if microgranulomas confer a similar phenotype. This study sought to define the incidence of microgranulomas in pediatric CD and compare the clinical course with cases with granulomas and those without granulomatous inflammation. METHODS We performed a single-center, retrospective study of pediatric CD patients who had at least 3 years of follow-up. Initial diagnostic biopsies were systematically re-examined by a gastrointestinal pathologist. A priori definitions of granuloma (10+ histiocytes) and microgranuloma (4-9 histiocytes) were used. Disease outcomes of hospitalization, development of complicated disease behavior, perianal disease, and the use of anti-TNF therapy were assessed by Kaplan-Meier survival plots. RESULTS This study included 138 subjects with an average follow-up of 4.6 years. Granulomas were seen in 38 of 138 subjects (27.5%) and an additional 38 subjects (27.5%) had at least one microgranuloma (in the absence of granulomas). Escalation to anti-TNF therapy was higher in CD with granulomas (p = 0.001) and microgranulomas (p = 0.0001) compared to those without granulomatous inflammation. CONCLUSION A significant subset of pediatric CD patients have microgranulomas (in the absence of well-defined granulomas). Children with CD who have microgranulomas are escalated to anti-TNF therapy more frequently than those without granulomatous inflammation (and at a similar rate to those with granulomas). Pathologists should have a low threshold to report microgranulomas as they may help to predict disease behavior.