T-cell-rich B-cell lymphoma presenting in the spleen: a clinicopathologic analysis of 3 cases.

We review the clinical, pathologic, and molecular genetic features of 3 splenic T-cell-rich B-cell lymphomas and discuss their differential diagnosis. All patients presented with symptomatic splenomegaly and underwent diagnostic/therapeutic splenectomy. Microscopically, the spleen in all cases showed a micronodular proliferation of lymphoid cells. A proportion of the nodules demonstrated central hyalinization or sclerosis. There was also an exuberant extramedullary hematopoiesis. On immunohistochemical stain, the nodules consisted predominantly of small T cells with scattered large atypical B cells. The clonal nature of the atypical B cells was confirmed by polymerase chain reaction assays for immunoglobulin heavy-chain gene rearrangement. In the H&E sections, the differential diagnoses included Hodgkin's lymphoma, follicular lymphoma, peripheral T-cell lymphoma, and nonneoplastic granulomatous process. The presence of exuberant extramedullary hematopoiesis also raised the possibility of a chronic myeloproliferative disorder. The combined morphologic, immunohistochemical, and molecular genetic data are essential for a correct diagnosis of splenic T-cell-rich B-cell lymphoma.