CD20-positive T-cell lymphoma involving bone marrow: report of four cases

Lymphomas are classified based on clinical presentation, morphology, immunophenotyping and molecular studies. Non-Hodgkin lymphomas are broadly divided into B cell and T/NK cell types [1]. Historically, CD20 has been regarded as a specific B-cell marker and has been used to distinguish mature B-cell from T-cell neoplasms [2]. However, several reports have shown CD20 expression in peripheral T-cell lymphomas diagnosed in lymph nodes, skin lesions, mediastinal masses, adrenal masses, gastric lesions, and pancreatic masses [3-7]. In this report, we describe four patients with CD20-positive T-cell lymphomas involving the bone marrow. Although little is known about the prognostic significance of CD20 expression in T-cell lymphomas, its identification may cause diagnostic difficulty. Therefore, a combination of morphologic examination, immunophenotypic analysis with a broad panel of antibodies, and molecular studies is necessary for determination of the cell lineage and making a correct diagnosis.