New defining body (Ugras body) in polypoid dedifferentiated liposarcoma of the vallecula. Histomorphological, immunohistochemical and molecular genetic findings.

This is a description of a dedifferentiated liposarcoma seen in a 27-year-old female patient. The tumor originated from the vallecula and contains distinctive bodies. These bodies, which are formed by the aggregation of tumor cells, contain collagen in several regions and are oval or elongated in shape. Immunohistochemically, the tumor cells showed staining for MDM2, p16, Vimentin, beta catenin, smooth muscle actin, bcl-2 and p53. Ki-67 ratio was 17% in hypercellular areas of the tumor. Molecular genetic studies have found copy number increase for CDK4 and MDM2 genes. Final histopathological diagnosis was dedifferentiated liposarcoma with unique bodies. Although meningothelial-like whorls is defined in dedifferentiated liposarcoma, this body has not been defined until now. To our knowledge, this is the first case of a DDL containing a cellular spindle cell component seen as rare sheet-like areas and distinctive ball-like, or elongated, serpiginous formations in the middle of paucicellular, collagenous areas.