FUS/TLS-CHOP chimeric transcripts in liposarcoma tissues

Myxoid liposarcoma and malignant fibrous histiocytoma (MFH) are common soft tissue sarcomas of adulthood. Histopathologically they often show intratumor heterogeneity. In some cases, differential diagnosis of liposarcoma and MFH is difficult. It has been reported that myxoid liposarcomas are characterized by chromosomal translocation t (12; 16) (q13; p11), and that this results in two types (type I and type II) of FUS/TLS-CHOP fusion transcripts. In this study, the FUS/TLS-CHOP chimeric transcripts in seven malignant soft tissue tumors of Asian patients were analyzed by reverse transcription-polymerase chain reaction, DNA blot hybridization and nucleotide sequencing. One myxoid liposarcoma and two round cell liposarcomas possessed a chimeric transcript whose fusion point was the same as that of the type I fusion transcript reported previously for myxoid liposarcoma. We were thus able to detect the type I FUS/TLS-CHOP fusion transcript in clinical specimens of liposarcoma from Asian patients, including the first examples of round cell liposarcoma. These results suggest that the detection of FUS/TLS-CHOP chimeric transcripts or chimeric genes can be used as a diagnostic tool for the pathological diagnosis of liposarcomas.