Richter transformation
Transformation of chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) into a more aggressive type of lymphoma, usually diffuse large B-cell lymphoma (immunoblastic or centroblastic variant). Occasional cases of transformation to Hodgkin's lymphoma have also been described, particularly in patients treated with purine nucleotide analogs. Molecular genetic studies suggest that in approximately half of the cases, the lymphoma is clonally related to the underlying CLL/SLL, whereas in the remaining cases the lymphoma probably represents a secondary, unrelated neoplasm.