Richter syndrome: A rare complication of chronic lymphocytic leukemia or small lymphocytic lymphoma.

Background: Richter's syndrome (RS) is a rare complication with an unfavorable prognosis, in which chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) transform into a more aggressive type of lymphoma, most commonly into diffuse large B cell lymphoma (DLBCL) or less often into Hodgkin's lymphoma (HL).
Objectives: The objective of this research paper was to present a retrospective analysis of patients with CLL/SLL whose disease transformed into RS.
Material and Methods: The study included 217 patients (100 women and 107 men) with CLL/SLL diagnosed in the years 2006-2015 at the Department of Hematooncology and Bone Marrow Transplantation of the Medical University of Lublin, which transformed into RS. We analyzed clinical, laboratory, immunophenotypic (ZAP-70 and CD38 expression), histopathological, and genetic data (del(17p), del(11q)), which was collected at the time of CLL/SLL diagnosis, and some which was collected at the time of transformation.
Results: Richter's syndrome was diagnosed in 4.6% of all CLL and SLL patients. The group of patients with RS consisted of 9 patients with primary CLL and 1 patient with a diagnosis of SLL (8 patients with transformation into DLBCL and 2 patients with transformation into HL). Leukemic lymphocytes showed evidence of peripheral blood lymphocyte membrane expression of ZAP70+/CD38+ (1 patient), of ZAP-70+/CD38- (3 patients), of ZAP-70-/CD38- (1 patient), and of ZAP-70-/CD38+ (5 patients). The deletion of 11q (del(11q)) was documented in 2 patients. In 4 cases, the location of RS was extremely rare (the thyroid gland, liver, skin, bladder, and central nervous system).
Conclusions: Richter's syndrome is a rare, but probable complication of CLL/SLL with an unfavorable prognosis, and it should be taken into account at every stage of the disease, particularly when the course of the disease is aggressive.