By examination of both protein markers (cell-surface immunoglobulin) and DNA markers (immunoglobulin-gene rearrangements), “biclonal B-cell lymphoma” was proposed. However, the further investigation revealed that genotypic and phenotypic biclonal B cell lymphomas were derived from a single progenitor cell. We present here a case of true biclonal B-cell lymphoma, in which change in clones occurred accompanied by the morphologic transformation of follicular lymphoma to diffuse lymphoma.
A 59-year-old Japanese male was found to have right-sided cervical lymphadenopathy and tonsillar swelling. In April, 1986, a cervical lymph node biopsy was performed and was interpreted as showing malignant lymphoma, follicular mixed small cleaved cell and large cell. The lymphoma cells expressed monoclonal surface immunoglobulins and they had a karyotype of 47, XY, +12, t(3;14) (q27;q32). He was diagnosed as having the clinical stage II disease and he received treatment of irradiation. After a remission of 18 months duration, again he noticed lymph node swelling on the both-sided cervical region, and was readmitted to our hospital because of increasing difficulty in breathing. In February, 1988, he underwent an emergency tracheotomy and the second lymph node biopsy, which revealed malignant lymphoma, diffuse large cell. The lymphoma cells did not express any surface immunoglobulin. However, they were shown to be of B cell origin by the positive reaction to monoclonal antibodies of CD19(B4), CD20(B1), and CD21(B2). And the modal karyotype was 48, XY, +21, t(2;7) (q31;q34), +der(7) t(2;7) (q31;q34). The patient was treated with a variety of combination chemotherapies, initially with VEPA followed by intermediate dose of MTX combined with other cytotoxic drugs. But the tumor was refractory to these treatments, and his condition rapidly deteriorated and he died of respiratory insufficiency in September, 1988. Southern blot analysis of immunoglobulin heavy chain gene, using the JH region probe, indicated the differently rearranged configurations before and after the histologic transformation. Therefore, this is the first case of transformed follicular lymphoma in which the tumor clone changed.
