Characterization of the blast cell in childhood non-Hodgkin's lymphoproliferative malignancies

Studies of cytomorphology, cytochemistry, phagocytosis and surface membrane markers for T- and B-lymphocyte characteristics have led to the realization that the traditional separation of ALL and NHL is invalid. Patient characteristics, clinical presentation, distribution of disease at diagnosis, response to therapy, remission duration, sites of relapse and survival all appear to correlate better with characterization and classification by the type of blast cell identified rather than with presence or absence of bone marrow involvement at diagnosis. Clearly, leukemias and lymphomas with cytomorphologically and cytochemically distinctive Burkitt's tumor cells which have monoclonal IgM on their surface are the same disease. In addition many clinical similarities are present in these patients whether or not the bone marrow is involved. Likewise, patients with sheep erythrocyte positive blast cells have similar diseases whether or not the marrow is involved. Subtypes of surface marker negative ALL and NHL will certainly be defined when the studies described above are routinely performed. Morphologic and cytochemical subtypes are recognizable and studies with (T cell antigen) HTLA and HBLA antisera suggest that further subclassification is possible. Whether these differences will be clinically, prognostically, and therapeutically useful must await the test of time. Attempts to stage childhood ALL and NHL on the basis of expected prognosis will certainly benefit from the additional input of careful characterization of the blast cells in these disorders. Careful pretreatment staging of children with non-Hodgkin's lymphoproliferative malignancies will in the future lead to more specific and effective therapy and improved remission duration and survival. (111 references).