Immunohistochemistry of Small Round Blue Cell Tumors of Childhood

Abstract

Small round blue cell tumors in childhood represent a diagnostic category of tumors that show no distinguishing morphologic features but require accurate identification because of their requirement for specific therapies and different clinical outcomes. While the use of ancillary investigations such as cell culture, cytogenetics, and molecular analysis has contributed to their identification and our understanding of their pathogenesis, electron microscopy and immunohistology have proven to be the most practical diagnostic tool in this category of tumors. In the majority of cases, a carefully selected panel of antibodies allows the identification of rhabdomyosarcoma, leukemia/lymphoma, neuroblastoma, Ewing's sarcoma/peripheral neuroepithelial tumors, desmoplastic small round cell tumor, and mesenchymal chondrosarcoma. Although no single antibody is specific, the combination of a number of positive and negative markers produces an immunohistochemical profile that is relatively specific to each of these tumors. To aid understanding of the immunophenotype and histogenesis, molecular aspects of each lesion is briefly discussed. (The J Histotechnol 22:239, 1999)