Extramedullary and extranodal manifestations in chronic lymphocytic leukemia - an update

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is a common leukemia characterized by clonal expansion of mature CD5+/CD23 + B cells in the blood, bone marrow (BM) and lymphoid tissues. CLL can undergo extramedullary and extranodal infiltration, with one study noting an incidence of only 0.3 per 100,000 people, and in 17.6% of CLL patients in another report. The most common extranodal sites of leukemic involvement are the skin and central nervous system; however, other organs, including liver, lungs, kidney, gastrointestinal tract, bone, prostate and heart, are occasionally involved. The prognostic significance of extra-medullary CLL is still under debate, but the prognosis in such patients seems to be better in the era of novel targeted drugs. Following a diagnosis of extranodal CLL, survival appears to depend on the site of infiltration. This review presents an overview of CLL in patients with extramedullary and extranodal leukemic lesions, focusing on its epidemiology, pathogenesis, prognosis, clinical characteristics and treatment results.