Splenic Lymphoma with Villous Lymphocytes

Splenic lymphoma with villous lymphocytes (SLVL) is a recently identified B cell lymphoproliferative disorder characterised by splenomegaly and the presence in the peripheral blood of lymphocytes with 'villous' projections. These villous lymphocytes are slightly larger than those found in CLL, have a round nucleus, a visible nucleolus in 50% of cases and have a variable amount of basophilic cytoplasm and characteristically, an irregular cell surface with thin, short membrane villi that are unevenly distributed and most often seen at the poles of the cell. Small numbers of plasmacytoid cells are present in most cases. There may be a variable degree of anaemia or thrombocytopenia. Immunologically the cells display a B cell phenotype with surface immunoglobulin of moderate to strong intensity, CD19, CD20, CD22, class II MHC antigens and FMC-7 expression, but they are often negative with CD5 and CD23, commonly positive in CLL, and they also are negative with CD25, HC2 and B-ly-7, typical markers in hairy cell leukaemia (HCL). The expression of CD11c, another HCL marker is variable. The bone marrow is easily aspirated and splenic infiltration is predominantly in the white pulp, both features distinct from HCL. A monoclonal gammopathy (M-band) is identified in the serum in two-thirds of patients, occasionally with free urinary light chains, but is generally less than 20 g/l. The disease usually follows a benign clinical course but may undergo transformation to large cell lymphoma in a minority of cases. When treatment is required, splenectomy is the treatment of choice and should be considered before splenic irradiation or chemotherapy which are less effective modalities.