Richter transformation with c-MYC overexpression: report of three cases.

Pathogenesis of Richter transformation (RT) or Richter syndrome (RS) of chronic lymphocytic leukemia (CLL) is still largely unknown. Increasing evidences show that c-MYC may play a role in the development of RS. Here we report three cases of RS with overexpression of c-MYC. The first case was a 78-year-old male who initially presented with CLL and then developed diffuse lymphadenopathy and ascites shortly after. Ascites cytology showed a population of large lymphoid cells positive for MYC (8q24) rearrangement by fluorescence in situ hybridization (FISH) and overexpression of c-MYC by immunohistochemistry (IHC). The second case was a 66-year-old male presented with rapidly enlarging lymph nodes and pleural effusion after a long history of CLL. Biopsy showed large B-cells positive for c-MYC overexpression and high Ki-67 proliferation index (80-90%). The third case was a 62-year-old female with CLL who presented for lobectomy for lung adenocarcinoma. Interestingly, along with the carcinoma, large B-cell lymphoma was incidentally found which had the same immunophenotype as the CLL. FISH analysis revealed gain of c-MYC at 8q and IHC showed increased c-MYC expression. This study supports that c-MYC plays a critical role in RS.