Small B-cell lymphomas of the spleen: How to tell them apart

Abstract

Various subtypes of small B-cell lymphoma can involve the spleen, and their classification in splenectomy specimens may be challenging. Accurate diagnosis of these entities may be critical to ensuring appropriate treatment and prognostication. We describe the types of small B-cell lymphoma that may involve the spleen and their differential diagnosis, using splenic compartment of involvement (white pulp vs. red pulp) as a diagnostic framework. Published literature on various lymphomas of the spleen, with an emphasis on recently recognized entities and emerging molecular genetic data, is reviewed. A multifaceted approach to diagnosis, using clinical and laboratory data, morphology, immunophenotype, and molecular genetic testing, is discussed. Although relatively few small B-cell lymphoma entities involve the spleen primarily, many systemic lymphomas may involve the spleen secondarily, and some recently described entities are encountered with relative infrequency. Fortunately, an understanding of the unique anatomy of the spleen as reflected by its unusual diversity of functions, in concert with a multiparameter approach to diagnosis, can help in narrowing this broad differential diagnosis considerably, in order to reach a specific diagnosis with certainty.