Surface immunoglobulin positive lymphoblastic leukemia in adults; a genetic spectrum.

Precursor B-lymphoblastic leukemia is typically surface immunoglobulin (sIg) negative. Although rare cases of sIg+ precursor lymphoblastic leukemia are recognized, sIg+ leukemia often represent leukemic phase of Burkitt lymphoma or other non-Hodgkin lymphoma such as blastic mantle cell lymphoma. This study reports four adults, two women (56 and 58 years old) and two men (35 and 41 years old) with lymphoblastic leukemia that displayed lambda, surface immunoglobulin restriction (sIg+). The leukemic cells were all dim CD45 positive with side scatter light characteristic of blasts. Two cases were positive with the blasts associated with antigens TdT and CD34. Genetic abnormalities were detected in all cases and in three cases included abnormalities commonly present in precursor lymphoblastic leukemia. Translocation (1;19) (q23;p13) was present in the first case. Deletion of the 3' region of the mixed lineage leukemia (MLL) gene at chromosome 11q23 as well as t(14;18) were detected in the second case. In the 3rd case, a BCR-ABL fusion gene was detected as part of a complex abnormal karyotype. Translocation (1;19)(q23;p13) was present in one case. Deletion of the 3' region of the mixed lineage leukemia (MLL) gene at chromosome 11q23 as well as t(14;18) were detected in one case. BCR-ABL fusion gene was detected as part of a complex abnormal karyotype in one case. These cases illustrate that lymphoblastic leukemias occurring in adults exhibit a morphologic, immunophenotypic as well as a genetic spectrum and represent either non-Hodgkin lymphoma or precursor lymphoblastic leukemia. A multi-parameter approach including flow cytometric and genetic studies is crucial in separating these cases.