Rhabdomyosarcoma: A malignant solid tumor arising from mesenchymal tissues which normally differentiate to form striated muscle. It can occur in a wide variety of sites. It is divided into four distinct types: pleomorphic, predominantly in male adults; alveolar (RHABDOMYOSARCOMA, ALVEOLAR), mainly in adolescents and young adults; embryonal (RHABDOMYOSARCOMA, EMBRYONAL), predominantly in infants and children; and botryoidal, also in young children. It is one of the most frequently occurring soft tissue sarcomas and the most common in children under 15. (From Dorland, 27th ed; Holland et al., Cancer Medicine, 3d ed, p2186; DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, pp1647-9)Rhabdomyosarcoma, Embryonal: A form of RHABDOMYOSARCOMA arising primarily in the head and neck, especially the orbit, of children below the age of 10. The cells are smaller than those of other rhabdomyosarcomas and are of two basic cell types: spindle cells and round cells. This cancer is highly sensitive to chemotherapy and has a high cure rate with multi-modality therapy. (From Holland et al., Cancer Medicine, 3d ed, p2188)Rhabdomyosarcoma, Alveolar: A form of RHABDOMYOSARCOMA occurring mainly in adolescents and young adults, affecting muscles of the extremities, trunk, orbital region, etc. It is extremely malignant, metastasizing widely at an early stage. Few cures have been achieved and the prognosis is poor. "Alveolar" refers to its microscopic appearance simulating the cells of the respiratory alveolus. (Holland et al., Cancer Medicine, 3d ed, p2188)Muscle Neoplasms: Tumors or cancer located in muscle tissue or specific muscles. They are differentiated from NEOPLASMS, MUSCLE TISSUE which are neoplasms composed of skeletal, cardiac, or smooth muscle tissue, such as MYOSARCOMA or LEIOMYOMA.PAX7 Transcription Factor: A paired box transcription factor that is involved in EMBRYONIC DEVELOPMENT of the CENTRAL NERVOUS SYSTEM and SKELETAL MUSCLE.Paired Box Transcription Factors: A family of transcription factors that control EMBRYONIC DEVELOPMENT within a variety of cell lineages. They are characterized by a highly conserved paired DNA-binding domain that was first identified in DROSOPHILA segmentation genes.Soft Tissue Neoplasms: Neoplasms of whatever cell type or origin, occurring in the extraskeletal connective tissue framework of the body including the organs of locomotion and their various component structures, such as nerves, blood vessels, lymphatics, etc.Orbital Neoplasms: Neoplasms of the bony orbit and contents except the eyeball.Urogenital Neoplasms: Tumors or cancer of the UROGENITAL SYSTEM in either the male or the female.Sarcoma: A connective tissue neoplasm formed by proliferation of mesodermal cells; it is usually highly malignant.Mesenchymoma: A mixed mesenchymal tumor composed of two or more mesodermal cellular elements not commonly associated, not counting fibrous tissue as one of the elements. Mesenchymomas are widely distributed in the body and about 75% are malignant. (Dorland, 27th ed; Holland et al., Cancer Medicine, 3d ed, p1866)Sarcoma, Ewing: A malignant tumor of the bone which always arises in the medullary tissue, occurring more often in cylindrical bones. The tumor occurs usually before the age of 20, about twice as frequently in males as in females.Chromosomes, Human, Pair 13: A specific pair of GROUP D CHROMOSOMES of the human chromosome classification.Forkhead Transcription Factors: A subclass of winged helix DNA-binding proteins that share homology with their founding member fork head protein, Drosophila.Oncogene Proteins, Fusion: The GENETIC TRANSLATION products of the fusion between an ONCOGENE and another gene. The latter may be of viral or cellular origin.Desmin: An intermediate filament protein found predominantly in smooth, skeletal, and cardiac muscle cells. Localized at the Z line. MW 50,000 to 55,000 is species dependent.Chromosomes, Human, Pair 2: A specific pair of human chromosomes in group A (CHROMOSOMES, HUMAN, 1-3) of the human chromosome classification.Vaginal Neoplasms: Tumors or cancer of the VAGINA.Combined Modality Therapy: The treatment of a disease or condition by several different means simultaneously or sequentially. Chemoimmunotherapy, RADIOIMMUNOTHERAPY, chemoradiotherapy, cryochemotherapy, and SALVAGE THERAPY are seen most frequently, but their combinations with each other and surgery are also used.Translocation, Genetic: A type of chromosome aberration characterized by CHROMOSOME BREAKAGE and transfer of the broken-off portion to another location, often to a different chromosome.Sertoli-Leydig Cell Tumor: A sex cord-gonadal stromal tumor consists of LEYDIG CELLS; SERTOLI CELLS; and FIBROBLASTS in varying proportions and degree of differentiation. Most such tumors produce ANDROGENS in the Leydig cells, formerly known as androblastoma or arrhenoblastoma. Androblastomas occur in the TESTIS or the OVARY causing precocious masculinization in the males, and defeminization, or virilization (VIRILISM) in the females. In some cases, the Sertoli cells produce ESTROGENS.Myogenin: A myogenic regulatory factor that controls myogenesis. Myogenin is induced during differentiation of every skeletal muscle cell line that has been investigated, in contrast to the other myogenic regulatory factors that only appear in certain cell types.MyoD Protein: A myogenic regulatory factor that controls myogenesis. Though it is not clear how its function differs from the other myogenic regulatory factors, MyoD appears to be related to fusion and terminal differentiation of the muscle cell.Vincristine: An antitumor alkaloid isolated from VINCA ROSEA. (Merck, 11th ed.)Cell Line, Tumor: A cell line derived from cultured tumor cells.Thoracic NeoplasmsTumor Cells, Cultured: Cells grown in vitro from neoplastic tissue. If they can be established as a TUMOR CELL LINE, they can be propagated in cell culture indefinitely.Pelvic Neoplasms: Tumors or cancer of the pelvic region.Gene Expression Regulation, Neoplastic: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in neoplastic tissue.Dactinomycin: A compound composed of a two CYCLIC PEPTIDES attached to a phenoxazine that is derived from STREPTOMYCES parvullus. It binds to DNA and inhibits RNA synthesis (transcription), with chain elongation more sensitive than initiation, termination, or release. As a result of impaired mRNA production, protein synthesis also declines after dactinomycin therapy. (From AMA Drug Evaluations Annual, 1993, p2015)Gene Fusion: The GENETIC RECOMBINATION of the parts of two or more GENES resulting in a gene with different or additional regulatory regions, or a new chimeric gene product. ONCOGENE FUSION includes an ONCOGENE as at least one of the fusion partners and such gene fusions are often detected in neoplastic cells and are transcribed into ONCOGENE FUSION PROTEINS. ARTIFICIAL GENE FUSION is carried out in vitro by RECOMBINANT DNA technology.Enterovirus A, Human: A species of ENTEROVIRUS infecting humans and containing 10 serotypes, mostly coxsackieviruses.Pulmonary Blastoma: A malignant neoplasm of the lung composed chiefly or entirely of immature undifferentiated cells (i.e., blast forms) with little or virtually no stroma. (From Stedman, 25th ed)Nephroblastoma Overexpressed Protein: A CCN protein family member found at high levels in NEPHROBLASTOMA cells. It is found both intracellularly and in the EXTRACELLULAR MATRIX and may play a role in the regulation of CELL PROLIFERATION and EXTRACELLULAR MATRIX synthesis.