Myxoid liposarcoma with adipocytic maturation: detection of TLS/CHOP fusion gene transcript

This report describes a 49-year-old woman with a well-circumscribed nodule of liposarcoma. The patient noticed a soft, slowly growing mass at the right sural region. Both axial computed tomography and magnetic resonance imaging revealed a soft tissue tumor consisting of nonfatty lesion measuring 5 x 3 x 3 cm circumscribed by a 1-cm thickened fatty area. Histologically, the tumor was made of 2 distinct components: the inner component of the tumor was a classic myxoid liposarcoma with numerous lipoblasts; the outer component was a lipoma-like lesion consisting of mature adipocytes without atypical nuclei. Immunohistochemically, MDM2 overexpression was observed and p53 immunophenotype was negative in both components. Molecular analysis revealed that type 1 TLS/ CHOP fusion gene transcript, characteristic of myxoid/round cell liposarcoma, was detected in both areas.