Non-germ-cell or teratomatous malignant tumors showing additional rhabdomyoblastic differentiation, with emphasis on the malignant Triton tumor.

Non-germ-cell or teratomatous malignant tumors showing additional rhabdomyoblastic differentiation can be divided into three groups. Group I consists of tumors with only sarcomatous differentiation. Included in this group are malignant mesenchymoma, dedifferentiated chondrosarcoma, and the dedifferentiated retroperitoneal liposarcoma. Epithelial or Sertoli-Leydig cell elements represent the second component of tumors in group II. The best known tumor in this group is the malignant mullerian mixed tumor, but other well described tumors with rhabdomyosarcomatous differentiation are the carcinosarcoma, mullerian adenosarcoma, Sertoli-Leydig cell tumor, mammary cystosarcoma, and blastomas. Most of the tumors in groups I and II are derived from mesenchymal tissue. A neuroectodermal origin is shared by all tumors in group III. This includes the medulloblastoma, retinoblastoma and, most frequently, the malignant Triton tumor. The tumors in all three groups are clinically malignant to a varying degree.