Identification of splenic marginal zone lymphoma from B lymphoproliferative disorders by flow cytometry

Abstract

The splenic marginal zone lymphoma (SMZL) is a relatively rare chronic B lymphoproliferative disease, which primarily manifest increase of peripheral blood lymphocyte count and/or scale, and splenomegaly, while the peripheral superficial lymph nodes are often not swollen. Therefore, the splenectomy are usually needed to confirm the diagnosis, but the majority of patients could not accept such management, resulting in early difficult diagnosis. This study was purposed to explore the more prior way for diagnosis based flow cytometry (FCM). Six patients with suspected diagnosis of SMZL were used as research objects, 10 healthy bone marrow donors and 10 cases of chronic lymphocytic leukemia (CLL), 3 cases of hairy cell leukemia (HCL), 3 cases of lymphatic plasma cell lymphoma/Waldenströ's macroglobulinemia (LPL/WM) were selected as control. The immunophenotype of bone marrow cells were analyzed and compared by FCM using a panel of antibodies including CD45, CD5, CD10, CD19, CD20, CD22, CD23, CD25, CD103, CD11c, CD123, κ,λ, Cyclin D1, and combined with bone marrow cell morphology. The results indicated that 6 cases of suspected SMZL showed a large increase of lymphocytes and splenomegaly. Because absence of peripheral lymphadenopathy, 6 patients did not suffer from lymph node biopsy, only 1 patient underwent diagnostic splenectomy. The immunophenotypes of bone marrow in patients and controls were analyzed by FCM, as a result, except for the healthy donors, varying degrees of abnormal mature B cell clones were found in bone marrow of all patients, and the further differentiation from other B-cell tumors was performed through CD5, CD10 expression and combination with other B-cell phenotype. All 6 cases of SMZL patients expressed CD19(+) and CD20(+), but CD10 expression was negative, 4 patients expressed CD5(-), 2 patients expressed CD5(+). The expressions of CD23, CD38, ZAP-70, CD11c, CD103, CD123, Cyclin D1 were negative. The morphological examination of bone marrow cells showed velutinous abnormal lymphocytes. Combined with clinical characteristics, 6 patients were diagnosed as SMZL, 1 patient suffered from splenectomy because of concurrent hypersplenism, and this postoperative pathologic examination confirmed the patient with SMZL. Ten cases of CLL mainly expressed CD5, CD23; 3 cases of HCL had more typical morphology of "hair like" in addition to CD11c, CD103 and CD123 positive; 3 cases of LPL/WM had significantly increased light chain restriction expression, IgM, plasmacytoid lymphocytes. It is concluded that the FCM immunophenotype analysis can be used as a powerful tools for clinical diagnosis of SMZL.