Diagnosis of small round cell tumors of childhood.

Primitive tumors, especially in children, can be extremely difficult to diagnose by conventional means. A wide variety of new methods have appeared in biomedical research that are applicable to diagnosis. These include (but are not limited to) tissue culture, cytogenetics, molecular genetics, and immunophenotypic analysis. Application of these methods can both provide a diagnosis and resolve long standing ambiguity regarding the origin and relationship of several childhood tumors including: (1) the relationship of neuroblastoma to other neural tumors in children and young adults; (2) the origin of Ewing's sarcoma, a perennial enigma; (3) the relationship of embryonal to alveolar rhadomyosarcoma. These issues are resolved by demonstrating characteristic findings in each of these tumors as a result of the appropriate application of each of these methods. As a consequence, these tumors are understood in a different perspective, including striking changes in terminology, categorization, diagnosis, and therefore treatment. In particular, (1) neuroblastoma is distinguished biologically and diagnostically from all other neural tumors of children; (2) Ewing's sarcoma is revealed as a neural tumor; (3) primitive forms of alveolar rhabdomyosarcoma are defined and regrouped with the common forms.