Primary synovial sarcoma of the heart: a cytogenetic and molecular genetic analysis combining RT-PCR and COBRA-FISH of a case with a complex karyotype.

Synovial sarcomas usually occur in the soft tissues of the extremities of adolescents and middle-aged patients, in the vicinity of large joints. We present a patient with a synovial sarcoma of the left atrium and ventricle, which is an extremely rare location. Diagnosis was confirmed by reverse transcriptase polymerase chain reaction (RT-PCR), showing the t(X;18) fusion transcript. With a multicolor COmbined Binary RAtio labeling Fluorescence In Situ Hybridization (COBRA-FISH) technique, a complex karyotype evolved with identification of derivative chromosomes with multiplex rearrangements. This underscores the importance of molecular analysis of spindle cell tumors in unusual locations. Moreover, it shows that the presumed diagnostic translocation t(X;18) can be embedded in a sequence of other chromosomal rearrangements of which the function is as yet unknown.