—  SPECIALTY CONFERENCE  —

Gastrointestinal Pathology

Case 5 - Sclerosing (Idiopathic Retractile) Mesenteritis

Joel K. Greenson
University of Michigan
Ann Arbor, MI





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Clinical History:
A 74 year-old man presented with abdominal pain and symptoms of acute intestinal obstruction. Imaging studies showed a mass in the small intestinal. A segmental resection of the mid-jejunum was performed.

Pathologic Findings:
A 95 cm. length portion of small intestine was removed. An ill-defined multinodular mass was present within the mesentery that measured 6 x 5 x 2.5 cm. The cut surface of the mass was yellow-white with areas of calcification. The mucosa of the small bowel appeared normal. Microscopic examination revealed a fibroinflammatory lesion centered in the mesenteric fat. Small areas of fat necrosis were surrounded by intense inflammation and fibrosis. Lymphoid aggregates were scattered in a Crohn's-like fashion. In between the areas of fat necrosis were dense infiltrates of lymphocytes and plasma cells. The overlying mucosa looked completely normal. Some of the inflammation encroached on the deeper aspects of the muscularis propria. While no vasculitis was appreciated on the H and E stained sections, an elastin stain showed one damaged/obliterated vein. An immunostain for IgG4 was completely negative.


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Differential Diagnosis:
  • Fibromatosis (Desmoid)

  • GIST

  • Inflammatory myofibroblastic tumor

  • Inflammatory well-differentiated liposarcoma

  • Sclerosing Mesenteritis

  • Retroperitoneal Fibrosis

  • Crohns' disease

Discussion:
Sclerosing mesenteritis is a rare condition of unknown etiology. It is most often seen in patients between the ages of 50 and 80, with a 2:1 male predominance. Several studies have also suggested it is more common in Caucasians than African-Americans. The disease goes by many different names which in part can be explained by 3 different histologic features any one of which may be dominant in a given case/patient. In some patients, the process may be dominated by fat necrosis. The terms mesenteric lipodystrophy and mesenteric Weber-Christian disease have been used to describe such cases. In some instances chronic inflammation may dominate the histologic picture. Such cases have been termed mesenteric panniculitis, systemic nodular panniculitis, inflammatory pseudotumor, and xanthogranulomatous mesenteritis. When fibrosis dominates the histology, then names such as sclerosing mesenteritis, retractile mesenteritis, and sclerosing mesenteric lipodystrophy have been used. While some studies suggest these differing histologies may represent different stages of disease, other studies have not found this to be the case.

Making the diagnosis of sclerosing mesenteritis can be tricky when only a single histologic feature dominates the picture. Cases with a prominent fibrosing pattern may be mistaken for a GIST or a fibromatoses. Immunostains for CD117 and Beta-Catenin can help sort this out, although a subset of sclerosing mesenteritis cases have shown patchy positivity for CD117 when using antigen retrieval. Cases with a predominant inflammatory component may be confused with inflammatory liposarcoma. A recent study by Weaver and colleagues found that strong staining with MDM2 helped identify liposarcomas, however weak staining was seen in some cases of sclerosing mesenteritis and retroperitoneal fibrosis. The use of confirmatory FISH testing helped to exclude the weakly positive cases from being misidentified as liposarcomas. Distinguishing sclerosing mesenteritis from inflammatory myofibroblastic tumors may be difficult as both can stain for actin. Inflammatory myofibroblastic tumors tend to be more circumbscribed and some will stain with ALK-1. Differentiating retroperitoneal fibrosis from sclerosing mesenteritis depends mostly on the location of the disease rather than the histologic findings as the two may be part of a spectrum of disease. The lack of primary mucosal inflammatory disease helps distinguish sclerosing mesenteritis from Crohn's disease.

While most published reports on prognosis and treatment of sclerosing mesenteritis contain very few cases, there is one large follow-up study from the Mayo clinic with 92 patients bt Akram et al. This study found that 10% of patients responded to surgical resection alone, 20% responded to additional medical therapy after surgery and 38% responded to medical therapy alone. A combination of tamoxifen and prednisone was the most common and most effective form of medical treatment. Other medical therapies that have shown some success include colchicine, azathioprine, thalidomide, and methotrexate. Half of the patients in this study required no therapy at all, while a few patients died of their disease. Some patients had multifocal involvement with disease in the pancreas and retroperitoneum (retroperitoneal fibrosis) and a few had Sjogren's syndrome.

The histogenesis and etiology of sclerosing mesenteritis is unkown, although it clearly shares many similarities with other fibrosclerotic diseases such as retroperitoneal fibrosis, Reidel's thyroiditis and inflammatory pseudotumor of the orbit. A recent study by Chen and Montgomery found that 2 of 9 cases of sclerosing mesenteritis had marked IgG4 staining of plasma cells while 4 of 9 cases had moderated staining. Both of the patients with marked staining ended up dieing from their disease. While this was a small study it raises the possibility that sclerosing mesenteritis may be an IgG4 related disease.

Final Diagnosis:
Sclerosing (Idiopathic Retractile) Mesenteritis

Talking Points
  1. There are a wide variety of fibroinflammatory and neoplastic lesions of the mesentery.

  2. While most lesions can be diagnosed with a combination of H&E morphology and clinical history, special stains and molecular studies can play an important role in arriving at the correct diagnosis.

  3. Immunostains for CD117, Beta Catenin, MDM2, IgG4, Actin and ALK-1 as well as FISH will be discussed.

References:
  1. Weaver J, Goldblum JR, Turner S, Tubbs RR, Wang WL, Lazar AJ, Rubin BP. Detection of MDM2 gene amplification or protein expression distinguishes sclerosing mesenteritis and retroperitoneal fibrosis from inflammatory well-differentiated liposarcoma. Mod Pathol. 2008 Oct 3. [Epub]

  2. Kapsoritakis AN, Rizos CD, Delikoukos S, Kyriakou D, Koukoulis GK, Potamianos SP. Retractile mesenteritis presenting with malabsorption syndrome. Successful treatment with oral pentoxifylline. J Gastrointestin Liver Dis. 2008 17(1):91-4.

  3. Akram S, Pardi DS, Schaffner JA, Smyrk TC. Sclerosing mesenteritis: clinical features, treatment, and outcome in ninety-two patients. Clin Gastroenterol Hepatol. 2007 5(5):589-96.

  4. Ghosh P, Kum J. Mesenteric panniculitis and sclerosing mesenteritis: a continuum of inflammation fibrosis. Clin Gastroenterol Hepatol. 2007 5(5):A32.

  5. Lim CS, Singh Ranger G, Tibrewal S, Jani B, Jeddy TA, Lafferty K. Sclerosing mesenteritis presenting with small bowel obstruction and subsequent retroperitoneal fibrosis. Eur J Gastroenterol Hepatol. 2006 12:1285-7.

  6. Katsanos KH, Ioachim E, Michail M, Price AC, Agnantis N, Kappas A, Tsianos EV. A fatal case of sclerosing mesenteritis. Dig Liver Dis. 2004 36(2):153-6.

  7. Montgomery E, Torbenson MS, Kaushal M, Fisher C, Abraham SC. Beta-catenin immunohistochemistry separates mesenteric fibromatosis from gastrointestinal stromal tumor and sclerosing mesenteritis. Am J Surg Pathol. 2002 10:1296-301.

  8. Wang H, Recant W, Montag AG, Hart J. Pathologic quiz case. A large mesentric mass in 40-year-old man. Arch Pathol Lab Med. 2001 125(3):443-4.

  9. Sheikh RA, Prindiville TP, Arenson D, Ruebner BH. Sclerosing mesenteritis seen clinically as pancreatic pseudotumor: two cases and a review. Pancreas. 1999 18(3):316-21.

  10. Dehner LP, Coffin CM. Idiopathic fibrosclerotic disorders and other inflammatory pseudotumors. Semin Diagn Pathol. 1998 15(2):161-73.

  11. Kelly JK, Hwang WS. Idiopathic retractile (sclerosing) mesenteritis and its differential diagnosis. Am J Surg Pathol. 1989 13(6):513-21.

  12. Chen TS, Montgomery EA. Are tumefactive lesions classified as sclerosing mesenteritis a subset of IgG4-related sclerosing disorders? J Clin Pathol 2008 61:1093-1097.

  13. Emory TS, Monihan JM, Carr NJ, Sobin LH. Sclerosing Mesenteritis, Mesenteric Panniculitis and Mesenteric Lipodystrophy: A Single Entity. Am J Surg Pathol. 1997 21:392-398.