Can HMGI-C be used as an aid with MDM2 and CDK4 to differentiate liposarcoma subtypes from their mimics?

摘要

Purpose: Liposarcoma represents the most common soft tissue tumors in adults. The tumors are characterized by a high morphological diversity and a great variation in biological behavior. Atypical lipomatous tumors represent a distinctive subset of mesenchymal neoplasms featuring mature adipocytic differentiation. Histologically, atypical lipomatous tumor might be easily confused with lipoma. Conversely, dedifferentiated liposarcoma may be confused with other spindle cell/pleomorphic undifferentiated tumors. Methods: A group of liposarcomas was analyzed by investigating the MDM2, CDK4, and HMGI-C proteins. The study was extended to a group of lipomas and non-lipomatous sarcomas, to determine whether the immunohistochemical investigation of these proteins might play any diagnostic role. Results: Our data suggest that ordinary lipomas may form a molecular genetic and morphological continuum with atypical lipomatous tumor. At one end of the spectrum are lipomas characterized by HMGI-C activation and at the other end are atypical lipomatous tumors with overrepresentation of the HMGI-C, CDK4, or MDM2 proteins. These findings not only provide insights into the molecular pathogenesis of lipomatous tumors, but also indicate that the immunohistochemical analysis of HMGI-C, CDK4, or MDM2 may help to increase diagnostic accuracy. Conclusions: HMGI-C is a useful adjunct in the diagnosis of atypical lipomatous tumor and dedifferentiated liposarcoma and differentiates them from their mimics. Therefore, in our experience, HMGI-C expression alone is of rather limited value in the differential diagnosis of liposarcoma subtypes.