Heterogeneity of lymphoblastic malignancies in children.

Lymphocyte surface markers show that lymphoblastic lymphomata in children are a heterogeneous but related group of diseases. Lymphoblastic lymphomas of T cell type fall into at least three subgroups: (1) HTLA positive, E rosette negative, TdT positive phenotype, with characteristically high levels of TdT and some associated expression of C-ALL antigen on a small proportion of cells. (2) E rosette positive lymphoblasts with intermediate range of TdT positivity, and which express antigens specific for thymic cortical lymphocytes. (3) E rosette positive and C3d positive T lymphoblasts with low levels of TdT enzyme. B lymphoblastic lymphomas show a major subgroup characterised by surface IgM expression, with or without detectable cytoplasmic IgM, and which may express ALL antigen. A minor subgroup of B lymphoblastic disease, of predominantly nodal presentation, expresses surface IgM with some expression of C3d receptors. Therefore at least 3 T cell, and 2 B cell subgroups of lymphoblastic lymphoma can be described.