t(4;19)(q35;q13.1): A recurrent change in primitive mesenchymal tumors?

We report an apparently balanced t(4;19)(q35;q13.1) as the sole cytogenetic change in a highly malignant extraskeletal sarcoma in a 12-year-old-boy. Tumor cells were negative for all immunocytochemical markers except vimentin and neuron-specific enolase. Electron microscopy indicated chondroblastic differentiation. The tumor was categorized as a malignant sarcoma with differentiation toward extraskeletal mesenchymal chondrosarcoma. Reports of a similar translocation in an embryonal rhabdomyosarcoma (RMS) and in a dedifferentiated sarcoma with both rhabdomyosarcomatous and osteosarcomatous elements suggest that this translocation can arise in a primitive mesenchymal stem cell that can differentiate along at least these three pathways.