Adenosine deaminase positive, E receptor negative lymphoma.

The measurement of enzymatic activity in the blast cell is a recent investigational technique which seems to complement immunologic measurement of cell membrane receptors in childhood lymphoproliferative malignancies. We have identified a patient with non-Hodgkin's lymphoma, not readily classifiable on the basis of either morphology or cell surface markers, i.e., E rosette and SIg negative, EAC positive. Analysis of enzymatic function, however, revealed markedly elevated ADA activity and essentially normal TdT activity. ADA positive lymphoma can arise from a primitive T-cell line. It is, thus, apparent that the morphological description of malignant lymphoid lines must be accompanied by surface marker and enzymatic data in order to properly classify cell lineage and identify appropriate therapeutic modalities.