[Clinicopathologic study of splenic marginal zone B-cell lymphoma].

ABSTRACT

OBJECTIVE: To study the clinicopathologic features, diagnosis and differential diagnosis of splenic marginal zone B-cell lymphoma (SMZL). METHODS: The clinical data, histologic findings and immunophenotype of 8 SMZL cases were studied. IgH gene rearrangement was performed in 1 case. Follow-up information was available in 4 patients. RESULTS: The median age of the patients was 61.5 years (range 36 to 75 years). The male-to-female ratio was 1.71. All cases presented with massive splenomegaly. Five of six cases had abnormal blood counts neutropenia and thrombocytopenia with two of them showing anemia. After splenectomy, the blood counts in 3/3 cases returned to normal levels. Post-operative fludarabine-based chemotherapy was given to 3 patients, two of them achieved complete remission and 1 case died during the course of chemotherapy. The average survival time was 21.5 months (range 6 to 60 months). Histologically, all of the 8 cases showed micronodular white pulp lesions. Six of them exhibited the classic biphasic appearance with central aggregates of small B cells rimmed by a peripheral zone of atypical monocytoid B cells. The remaining 2 cases had a monomorphous appearance, consisting mainly of atypical monocytoid B cells. There was infiltration of tumor cells in the red pulp, sheets in appearance in all 8 cases. Immuno-histochemical staining showed CD20-positive (8/8), IgD-positive in 2 of the 4 cases (2/4), CD5-positive in 1 of the 4 cases (1/4), 6 of the 6 cases were bcl-2-positive, cyclin D1-negative and bcl-6/CD10-negative, CD43-negative in 5 of the 6 cases (5/6). The proliferation index, as highlighted by Ki-67 immunostaining, was low (< 15%). CONCLUSIONS: SMZL is an indolent B-cell non-Hodgkin lymphoma. The main clinical manifestations are splenomegaly and abnormalities in blood counts. The main modality of treatment is splenectomy. Adjuvant fludarabine-based chemotherapy helps to achieve complete remission. In general, the prognosis of this lymphoma type is good. The lymphoma cells predominantly grow in micronodular pattern, with atypical monocytoid B cells rimming around the small B cells, which aggregates in the center. The differential diagnosis includes other small B-cell lymphomas and lymphoid hyperplasia of spleen.