A 67 year old female presented to an outside facility with four months of intermittent abdominal pain and alternating episodes of diarrhea and constipation. CT scan of the abdomen and pelvis showed a large lobulated mesenteric mass closely adherent to adjacent bowel and encasing the SMA and SMV. A CT-guided core needle biopsy performed and pathology was consistent with an inflammatory myofibroblastic tumor. Based on the location, the tumor was deemed unresectable. The patient established care at our facility for a second opinion. Over the next several months, she was hospitalized at our facility for recurrent episodes of small bowel obstruction (SBO) requiring hospitalization. Each time she was managed conservatively. Pathology slides from the prior biopsy were obtained and new immunohistochemical studies were performed. Based on the ratio of IgG4+ plasma cells to total IgG4 plasma cells, the findings were consistent with an IgG4-related fibrosclerosing process. The patient was subsequently treated with high dose prednisone and colchicine with no improvement.
Most recently, the patient was evaluated in the emergency department for nausea, vomiting, abdominal pain and altered mental status. She was afebrile and had no leukocytosis, but was tachycardic. Serum lactate was 3.7 mmol/L. CT scan of the abdomen and pelvis showed pneumoperitoneum with free fluid and apparent spillage of bowel contents into the peritoneal cavity. She was taken to the operating room emergently for small bowel resection and peritoneal washout. Intraoperatively, the patient developed septic shock, metabolic acidosis, and oliguria requiring intravenous fluid and vasopressor administration. She was admitted to the ICU in septic shock, with respiratory failure and pancytopenia. Her blood counts reached a nadir on Post-Operative Day 1 (POD1): hgb 5.8, WBC 1.7, platelets 49. She was successfully weaned off vasopressin and norepinephrine on POD1 and was extubated on POD2. The patient was discharged to a rehabilitation facility on IV antibiotics on hospital day 9. Operative pathology was consistent with a diagnosis of sclerosing mesenteritis, a rare manifestation of IgG4-related disease.
Discussion:
Sclerosing mesenteritis is a chronic inflammatory condition involving the adipose tissue surrounding the mesentery. IgG4-related disease is an immune-mediated condition characterized by elevated serum immunoglobulin levels and lymphoplasmacytic infiltration of involved structures. It is most commonly associated with autoimmune pancreatitis.
Conclusions:
Rare conditions can be difficult to diagnose and can delay appropriate treatment. This patient has IgG4-related sclerosing mesenteritis manifesting as a large fibrotic mass surrounding bowel and abdominal vasculature. More aggressive treatment, either with resection of the mass or with cytotoxic/immune-modulator therapy may have improved the patient’s medical course and possibly avoided the life-threatening complication of perforated abdominal viscus.