Characteristic clinicopathologic features of adult B-cell lymphoblastic lymphoma with special emphasis on differential diagnosis with an atypical form probably of blastic lymphocytic lymphoma of intermediate differentiation origin

Background. Lymphoblastic lymphoma is typically of thymic T-cell phenotype. Lymphoblastic lymphoma of B-cell origin (B-lymphoblastic lymphoma) has been relatively poorly described. Whether B-lymphoblastic lymphoma should be managed like its T-cell counterpart remains to be clarified. Methods. From 1983 to 1991, 10 adult patients were diagnosed as having B-lymphoblastic lymphoma at National Taiwan University Hospital by using the histomorphologic criteria of international working formulation. B-cell phenotype was determined by the immunohistochemistry method. Clinicopathologic features of these 10 patients were reviewed. Results. Seven patients were grouped as typical type and were characterized by an aggressive clinical course with lymph node (7 of 7), bone marrow (6 of 7), liver (3 of 7), spleen (3 of 7), and central nervous system (2 of 7) involvement. The median survival time was 8 months. In contrast, three patients had an atypical clinical picture. They were older patients (64–73 years) and were characterized by a relatively less aggressive course with predominantly bulky nodal involvement. Two of these three patients are alive (31 and 49 months, respectively) and well at this report, with one of them being repeatedly experiencing disease remission with the use of simple salvage chemotherapeutic regimens. Further studies revealed that tumor tissues of these three atypical cases had strong expression of CD5 (Leu-1) marker. Conclusion. B-lymphoblastic lymphoma diagnosed by histomorphologic criteria should be further distinguished from a relatively favorable subtype, which probably represents a variant of blastic lymphocytic lymphoma of intermediate differentiation as described by Lardelli et al.1 Clinical features of typical B-lymphoblastic lymphoma, except for the lack of mediastinal involvement, is similar to its T-cell counterpart.