S3069 A Disease of Many Names: Sclerosing Mesenteritis

Abstract

Introduction: Sclerosing mesenteritis (SM) refers to a spectrum of inflammatory disorders of the bowel mesentery adipose tissue whose pathogenesis is poorly understood, but has been associated with prior abdominal surgery, malignancy, and autoimmune disease. Patients can be asymptomatic or have non-specific abdominal complaints. Diagnosis can be made radiographically, but tissue is required for definitive evaluation. We present a case of severe constipation and abdominal distention due to sclerosing mesenteritis. Case Description/Methods: A 55-year-old male presented with two months of constipation, abdominal pain, and severe distention impairing ability to wear regular-sized clothing. Initial laboratory evaluation was normal, CTAP revealed no obstruction, and colonoscopy was normal. A trial of linaclotide briefly improved symptoms, however he re-presented to an ED with severe pain where CTAP showed an ovoid expansile region of mesenteric haziness within the central abdomen, encircling the mesenteric root vessels, reflecting SM with mass effect on the surrounding bowel (Figure 1A). PET/CT did not show evidence of malignancy. Laparoscopic mesenteric biopsy revealed areas of fat necrosis with associated lipid-laden macrophages; fibrosis was not identified, plasma cells were not prominent, and IgG4 positive cells were absent. Immunostains were negative. Laboratory evaluation was notable for: borderline ANA titer 1:80, positive fibrillarin antibody, and negative Scl-70. Systemic steroids were initiated with some improvement in symptoms, and tamoxifen was later added. Discussion: Sclerosing mesenteritis is a rare inflammatory, fibrotic disease of bowel mesentery fat tissue whose presentation ranges from asymptomatic to severe pain and bowel changes due to obstruction. While its exact pathogenesis is unclear, it may be related to prior surgery, underlying malignancy (eg. lymphoma) or an autoimmune etiology (due to association with conditions such as primary sclerosing cholangitis and retroperitoneal fibrosis). Diagnosis is challenging; CT scan is the most sensitive test, but histological analysis is necessary to evaluate for any underlying etiologies. There is no definitive therapy, but systemic steroids and antifibrotic agents such as tamoxifen have been studied; some patients require surgical resection.Figure 1.: CT-Abdomen and Pelvis: An ovoid expansile region of mesenteric haziness within the central abdomen, encircling the mesenteric root vessels, reflecting sclerosing mesenteritis with mass effect on the surrounding bowel loops.