Histologic transformation of chronic lymphocytic leukemia/small lymphocytic lymphoma

Although generally considered a clinically indolent neoplasm, CLL/SLL may undergo transformation to a clinically aggressive lymphoma. The most common form of transformation, to DLBCL, is also known as Richter syndrome. Transformation determines the course of the disease and is associated with unfavorable patient outcome. Precise detection of transformation and identification of predictive biomarkers and specific molecular pathways implicated in the pathobiology of transformation in CLL/SLL will enable personalized therapeutic approach and provide potential avenues for improving the clinical outcome of patients. In this review, we present an overview of the pathologic features, risk factors, and pathogenic mechanisms of CLL/SLL transformation. Am. J. Hematol. 91:1036–1043, 2016.