Sclerosing Mesenteritis in a Patient Heterozygous for Factor V Leiden.

BACKGROUND Sclerosing mesenteritis is an inflammatory and fibrotic disease that affects the mesentery of the small intestine. This condition is non-neoplastic, although it is frequently associated with underlying malignancies. The overall etiology is unclear because of the limited number of cases available for review, yet a number of possible mechanisms have been described, including ischemia. Factor V (FV) Leiden is a hereditary condition causing hypercoagulability, thrombosis, and ischemia. Because ischemia is one of the proposed mechanisms for the fibrosis and sclerotic findings of sclerosing mesenteritis, this case explores a possible association between FV Leiden and sclerosing mesenteritis. CASE REPORT Herein, we describe a case of sclerosing mesenteritis in a patient heterozygous for FV Leiden, with a strong personal and family history of venous thromboembolism. This patient presented with acute worsening of chronic abdominal pain and was found to have a small bowel obstruction requiring acute surgical intervention. Imaging findings and pathologic examination of the ileum and mesentery conclusively diagnosed sclerosing mesenteritis. CONCLUSIONS This case serves to highlight a possible association between mesenteric ischemia secondary to chronic thrombotic activity and sclerosing mesenteritis. This patient's virgin abdomen and lack of additional risk factors for sclerosing mesenteritis make this case a unique presentation of the disorder. This case serves to update the literature at large, as only one prior case in a FV Leiden patient has been described, in which the patient had the additional risk factor of previous abdominal surgery.

Detection of MDM2 gene amplification or protein expression distinguishes sclerosing mesenteritis and retroperitoneal fibrosis from inflammatory well-differentiated liposarcoma.

Inflammatory liposarcoma is a variant of well-differentiated liposarcoma/atypical lipomatous tumor that consists of a mixture of lymphocytes, histiocytes, scattered atypical stromal cells, mature adipocytes, and rarely lipoblasts. When the inflammatory infiltrate predominates, the morphological features overlap with various fibroinflammatory disorders including sclerosing mesenteritis and retroperitoneal fibrosis, making the diagnosis difficult. Well-differentiated liposarcoma/atypical lipomatous tumor and dedifferentiated liposarcoma have characteristic molecular markers in the form of giant marker and ring chromosomes consisting of amplicons of 12q13-15, which includes MDM2. MDM2 immunohistochemistry (IHC) (Zymed; clone IF2) and dual color fluorescence in situ hybridization utilizing MDM2 (12q15) and chromosome 12 centromeric probes were performed on formalin-fixed and paraffin-embedded specimens from inflammatory well-differentiated liposarcoma (17 cases), sclerosing mesenteritis (14 cases), and idiopathic retroperitoneal fibrosis (10 cases). MDM2 expression as detected by IHC is a very sensitive tool in recognizing inflammatory well-differentiated liposarcoma (17 of 17); however, 21% (3 of 14) and 10% (1 of 10) of sclerosing mesenteritis and retroperitoneal fibrosis, respectively, displayed weak MDM2 immunoexpression. The MDM2 fluorescence in situ hybridization assay was very specific for inflammatory well-differentiated liposarcoma as 15 of 17 (88%) cases showed MDM2 amplification, whereas none of the cases of sclerosing mesenteritis or idiopathic retroperitoneal fibrosis showed amplification. Five cases of retroperitoneal fibrosis were noncontributory secondary to autofluorescence, potentially limiting the usefulness of the assay in certain situations such as inappropriate fixation. Increased MDM2 expression and/or MDM2 amplification can be employed to aid discrimination of inflammatory well-differentiated liposarcoma from fibroinflammatory mimics. MDM2 fluorescence in situ hybridization is a very specific method (100%), but less sensitive (88%), whereas MDM2 expression by IHC is very sensitive (100%), but less specific (83%). Therefore, a positive screen of difficult cases with MDM2 IHC would require confirmation by the fluorescence in situ hybridization. However, lack of MDM2 immunoexpression would rule out the possibility of inflammatory well-differentiated liposarcoma.