CD56+CD7+stem cell leukemia lymphoma with D2-J delta 1 rearrangement

Object We describe the characteristics of three patients with CD56+CD7+ ste m cell leukemia/lymphoma. Methods These blasts were analyzed for morphologi c, karyotypic, immunophenotypic, and immunogenotypic features using Souther n blot and polymerase chain reaction analysis. Materials Peripheral blood, bone marrow aspirates, or biopsied mediastinal tumor specimens of three CD5 6+CD7+ stem cell leukemia/lymphoma patients were investigated. Results The bone marrow of all patients showed myeloperoxidase (MPO) negative blast cel ls with basophilic cytoplasm and distinct nucleoli with no azurophilic gran ules, The blasts of two patients were classified as acute lymphoblastic leu kemia (L2), The liver, spleen, and lymph nodes were unaffected in all patie nts. All had an aggressive clinical course. The blasts were strongly positi ve for both CD7 and CD56 but negative for other T-lineage associated antige ns, including CD1, CD2, surface membrane CD3, cytoplasmic CD3c (2/2), CD4, CD5 and CD8, The additional antigens were recognized as follows: CD19 (1/3 cases) as a B lineage, CD33 (1/3) as a myeloid marker, CD34 (2/3) as a stem cell, CD38 (1/1) and HLA-DR (2/3), When the patients relapsed, the phenoty pes changed to blasts positive for CD5, CD10 and CD13 in patient 1, CD5 in patient 2, and CD33 in patient 3. MPO, however, remained negative, Cytogene tic analysis showed no common abnormal karyotype, All had a common D2-J del ta 1 induced by T-cell specific enhancer. Rearrangement of TCR beta and gam ma genes occurred in patient 2, and IgH and TCR beta underwent rearrangemen t in patient 3. Conclusion Although a more comprehensive case analysis is n ecessary, these data suggest the possibility that the blasts of the present cases come from a common lymphoid precursor (T, NK, and B cell) or from a NKT precursor as the fourth lymphoid lineage.