Primary splenic B-cell lymphoma (marginal zone lymphoma). Clinicopathological evaluation of 10 cases

SMZL has been included in the REAL classification of lymphoid neoplasms (1994) as an entity. It affects middle aged adults presenting with splenomegaly, mild lymphocytosis and in 40% of cases with the presence of monoclonal paraprotein. Our material includes 10 patients (6 women + 4 men). In all patients bone marrow biopsy was the initial material for histopathological examination. With characteristic intertrabecular nodular interstitial infiltrates of CD20+ small lymphocytes and corresponding clinical data (splenomegaly, lymphocytosis in peripheral blood and sporadic elevation of IgM levels) it was very suggestive of SMZL diagnosis. Splenectomy was the treatment of choice. The spleen showed micronodular white foci in all cases. Morphologically the pattern of white pulp involvement was observed with lymphoma infiltrates as well as small foci in the red pulp. The white pulp showed follicles surrounded by a wide marginal zone, resembling reactive splenic follicles. A corona-like rim consisted of medium size cells with abundant clear cytoplasm, resembling monocytoid B cells, often with plasmacytoid differentiation, or centrocyte-like cells. Smaller aggregates of these cells were present in the red pulp. Lymphoma cells were CD20+, bcl-2 and IgM+. In all cases monoclonal kappa light chains were found. Although SMZL is a disseminated lymphoma at diagnosis, its course is indolent and splenectomy is the treatment of choice. Clinical and histopathological differential diagnoses include hairy cell leukemia and secondary involvement of the spleen by infiltrates of nodal B-cell lymphomas.