Aggressive CD5-positive B-cell lymphoma after remission of CD5-negative follicular lymphoma with distinct immunoglobulin heavy chain rearrangement and translocation.

We report a unique, aggressive B-cell lymphoma that developed after the long-term remission of follicular lymphoma (FL). FL cells were negative for CD5, whereas aggressive lymphoma cells were positive for CD5. In FL, one immunoglobulin heavy chain gene (IGH) allele underwent V/D/J recombination and another t(14;18)(q32;q21). In aggressive lymphoma, one IGH allele underwent D/J recombination and another translocation, but not t(14;18)(q32;q21). An aggressive lymphoma-specific D/J sequence was detected in FL tissue. Our results indicated that the two tumors arose from distinct B cells and that they existed concurrently in the same lymph node.