S1782 IgG4 Colitis and Infliximab Therapy

Abstract

INTRODUCTION: Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory condition. It is characterized by increased serum levels of IgG4 and tissue infiltration by IgG4 cells. It can involve multiple organs and if untreated the disease can lead to fibrosis and irreversible organ damage. IgG4-RD has mostly been described in adults and it's exact prevalence in pediatrics is unknown. We report a pediatric case of IgG4-positive sclerosing colitis who had dramatic response to Infliximab therapy. CASE DESCRIPTION/METHODS: 6 year old adopted male who was previously healthy presented to ER with acute onset of severe abdominal pain and fever. He was febrile with severe RLQ tenderness, guarding and minimal bowel sounds. Labs showed elevated WBC and CRP. US abdomen study did not visualize appendix. Subsequent MRI abdomen showed descending colitis with no evidence of obstruction, abscess or acute appendicitis. He soon developed abdominal distension and multiple episodes of bilious emesis. AXR obtained showed dilated loops of small bowel concerning for partial SBO, requiring NGT decompression. Stool studies including C. Diff returned negative. As he developed a SIRS picture with worsening abdominal distension, stat CT abdomen obtained showed bowel dilation without an obvious transition zone or pneumatosis but thickening of terminal ileum and left colon. Due to patient's worsening clinical picture, there was concern for possible compromised bowel or distal bowel obstruction not diagnosed by imaging, hence he underwent diagnostic ex-laparoscopy which showed thickening and inflammation of the left colon leading to segmental left colon resection and descending colostomy. Biopsies were taken and immunostaining was concerning for an IgG4 sclerosis colitis. Serum IgG4 level was elevated at 202. Patient was started on steroids followed by Infliximab as maintenance therapy. Repeat EGD/Colonoscopy prior to colostomy reversal showed normal biopsies and immunostaining. He responded well to Infliximab therapy with subsequent normal serum IgG4 levels. DISCUSSION: The pathogenesis of IgG4-RD remains incompletely understood. Study shows that small subset of patients with IBD can be characterized by high levels of serum and mucosal IgG4. These patients are generally prone to more severe and extensive lesions suggesting that high level of IgG4 may be a biomarker for a new subtype of IBD. The current literature in this area is sparse. Our case showed positive response to Infliximab therapy in IgG4 positive colitis.