[A case of IgG4-related sclerosing mesenteritis associated with Crohn's disease].

Sclerosing mesenteritis (SM) is a rare disease characterized by chronic nonspecific mesenteric inflammation and fibrosis of unknown etiology. Some tumefactive SM shows diffuse accumulation of IgG4-positive plasma cells and is considered as a part of the spectrum of IgG4-related disease. An association between inflammatory bowel disease and IgG4-related disease has been indicated. A 45-year-old woman visited our hospital due to weight loss with intermittent lower abdominal discomfort. Pelvic ultrasound revealed a mass-like lesion in the abdominal wall and pelvis MRI demonstrated a 5.9 cm sized wall-enhancing mass with heterogeneous signal intensity from right adnexa to the abdominal wall. Tumor resection and adhesiolysis was done because of severe adhesion with the small bowel, colon, bladder, uterus, and abdominal wall. Appendectomy was also performed due to adhesion and edematous change. Histological examination of the resected mass showed findings that were compatible with IgG4-related SM. The resected appendix showed chronic granulomatous inflammation without evidence of tuberculosis. She was diagnosed with Crohn's disease after undergoing colonoscopy and CT enterography. Herein, we report a rare case of IgG4-related SM that occurred in conjunction with Crohn's disease.