Application Of Previously Reported Lipo-Related Markers In Atypical Lipomatous Tumor/Well Differentiated Liposarcoma (Alt/Wdlps) And Lipoma

Background: In previous reports, several lipo-related markers have been introduced. Diagnosis of the atypical lipomatous tumor/well differentiated liposarcoma (ALT/WDLPS) is not easy, and we cannot exclude the influence of subjectivity when a differential diagnosis from lipoma is concerned. The aim of this study was to know the expression patterns of these markers in ATL/WDLPS and lipoma, and to evaluate whether these markers are helpful for the differential diagnosis between them. Material and Methods: Total 11 cases of ALT/WDLPS and 5 cases of lipoma previously diagnosed at St. Vincent's Hospital were reviewed, and immunohistochemistry for MDM2, CDK4, HMGI-C, FABP4, Calreticulin was performed on the specimen of these cases. Results: After slide review, four cases of previous ATL/WDLPS were proved as lipoma. With revision of the diagnosis, cases of ALT/WDLPS with characteristic histological findings showed positivity for both MDM2 and CDK4. In cases of benign lipoma, one of these markers were positive but not in both. HMGI-C, FABP4, and Calreticulin showed various and inconsistent positive reactions. Calreticulin was consistently expressed in ALT/WDLPS and lipoma. Conclusions: Histologic findings are most important in the diagnosis of ALT/WDLPS. In ambiguous cases, positivity for both MDM2 and CDK4 may be helpful for the diagnosis of ALT/WDLPS, but meticulous care is needed because positivity of MDM2 or CDK4 may also be observed in lipomas. HMGI-C, FABP4, and Calreticulin were inferior in terms of discrimination. Calreticulin is expected to be useful for identifying the lipogenic origin.