A rare chimeric TLS/FUS-CHOP transcript in a patient with multiple liposarcomas: A case report

Myxoid liposarcomas harbor a unique and specific t(12;16)(q13,p11) chromoso mal translocation. The breakpoint has recently been identified, and involve ment of the TLS/FUS gene on chromosome 16 and the CHOP gene on chromosome 1 2 was demonstrated. We report a case of a 45-year-old tt oman who developed multiple malignant lipomatous tumors of unknown origin and myxoid/round ce ll histology at different locations. To examine the diagnostic potential of this translocation and to develop a hypothesis on the origin of the tumors , we used cytogenetic and molecular cytogenetic methods (reverse transcript ion polymerase chain reaction, RT-PCR). We identified a chimeric RNA transc ript in the second recurrence in the thigh/groin, as rt ell as in another t umor in the mediastinum, which has an additional sequence of 33 bp, known a s fusion transcript type III. Cytogenetic analysis of another tumor in retr operitoneal space revealed a rare type of unbalanced translocation der(16)t (12;16). We hypothesize that these tumors are metastases rather than multic entric rumors. The detection of the chimeric message in the present case is not only useful for differential diagnosis, but also for analyzing the ori gin of multiple neoplasms. (C) Elsevier Science Inc., 1999. All rights rese rved.