Correlative ultrastructure and immunocytochemistry in small round cell tumors of childhood

Abstract

Conventional methods of pathologic evaluation of the undifferentiated solid tumors of childhood, often referred to as “small round cell tumors”, have been notoriously unreliable. Prior to the advent of effective therapy, this was of little consequence. Current treatment methods require precise categorization of these tumors, as tumor response shows wide variation, especially when inappropriate chemotherapeutic agents or radiation therapy are employed. The combination of transmission electron microscopy (TEM) and correlative immunocytochemistry (ICC) has proved to be a powerful tool in deriving precise diagnoses.The common small round cell tumors of childhood include sarcomas (especially undifferentiated rhabdomyosarcoma), lymphomas (especially lymphoblastic and large cell), neural tumors (neuroblastoma and a variety of apparently related neoplasms), and particularly Ewing's sarcoma, an enigmatic tumor of inapparent histogenesis with which all the above are compared. The treatment and prognosis of each of these groups is quite different, and we have attempted to reliably distinguish each from the other by ultrastructural and immunocytochemical criteria.