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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, AIMS, METHODS, RESULTS. Meshes: Adult, Aged, Arteries, Cell Count, Female, Humans, Immunoglobulin G, Immunohistochemistry, Lymphocytes, Male, Middle Aged, Panniculitis, Peritoneal, Phlebitis, Plasma Cells, Staining and Labeling, Veins.
user
Are tumefactive lesions classified as sclerosing mesenteritis a subset of IgG4-related sclerosing disorders? Context: The relationship between tumefactive lesions classified as sclerosing mesenteritis and IgG4-related sclerosing disorders (eg, lymphoplasmacytic sclerosing pancreatitis/autoimmune pancreatitis) remains uncertain. To review lesions coded as "sclerosing mesenteritis" for findings in keeping with IgG4-related sclerosing disorders. Inclusion in the study required available paraffin blocks for IgG4 staining and documentation of a mass lesion. A total of nine mesenteric lesions (3-14 cm) were identified in 6 male and 3 female patients. On H&E-stained sections, all were characterised as loosely marginated fibroinflammatory processes with variable amounts of fat necrosis. Lymphocytic venulitis/phlebitis was identified in 8 of 9 cases. IgG and IgG4 expression in lesional plasma cells was assessed by immunohistochemistry. IgG4-positive plasma cells were counted in the areas of greatest density in>or=3 high power fields (HPFs). The highest number per HPF was recorded and a score assigned based on the following scale:<5/HPF, none/minimal; 5-10/HPF, mild; 11-30/HPF, moderate;>30/HPF, marked. The relative proportion of IgG4-reactive plasma cells to total IgG-positive plasma cells was assessed. IgG4-reactive plasma cells ranged from 0 to>100 in the most dense zones (3 cases, none/minimal; 4 cases, moderate; 2 cases, marked).
assistant
Although this study is limited by small numbers, findings suggest that some tumefactive lesions regarded as sclerosing mesenteritis may be a subset of IgG4-related sclerosing disorders.