Delineation of Chondroid Lipoma: An Immunohistochemical and Molecular Biological Analysis

Aims. Chondroid lipoma (CL) is a benign tumor that mimics a variety of soft tissue tumors and is characterized by translocationt(11;16). Here, we analyze CL and its histological mimics.Methods. CL (n=4) was compared to a variety of histological mimics (n=83) for morphological aspects and immunohistochemical features including cyclinD1(CCND1). Using FISH analysis,CCND1andFUSwere investigated as potential translocation partners.Results. All CLs were strongly positive forCCND1. One of 4 myoepitheliomas,CCND1, was positive. In well-differentiated lipomatous tumors and in chondrosarcomas,CCND1was frequently expressed, but all myxoid liposarcomas were negative. FISH analysis did not give support for direct involvement ofCCND1andFUSas translocation partners.Conclusions. Chondroid lipoma is extremely rare and has several and more prevalent histological mimics. The differential diagnosis of chondroid lipomas can be unraveled using immunohistochemical and molecular support.