Incidence and Histologic Patterns of Bone Marrow Involvement of Malignant Lymphoma Based on the World Health Organization Classification- A Single Institution Study

Abstract

Working Formulation and Revised European American Classification of Lymphoid Neoplasms (REAL) have mainly been used in the studies for bone marrow involvement of malignant lymphoma in Korea. We investigated the incidence and histologic patterns of malignant lymphoma according to the WHO classification. This study included 507 cases of malignant lymphoma that were requested for bone marrow study for the staging during the period January 1999-December 2005 in Korea Cancer Center Hospital. Medical records, peripheral blood smears, bone marrow aspiration smears, biopsy sections, and histopathologic findings were analyzed retrospectively. Of the 507 cases of malignant lymphoma, 473 (93.3%) were non-Hodgkin lymphoma (NHL) and 34 (6.7%) were Hodgkin lymphoma (HL). The overall incidence of bone marrow involvement by NHL and HL was 12.5% (59/473) and 11.8% (4/34), respectively. Among NHL cases, the incidence of bone marrow involvement by B-cell and T-cell neoplasms was 11.4% (43/377) and 16.7% (16/96), respectively. Although the incidences of bone marrow involvement by several B-cell neoplasms were more than 30%, diffuse large B cell lymphoma showed a relatively low incidence of bone marrow involvement (4.6%). Of bone marrow involvement patterns, diffuse infiltration pattern was the most common (40.0%). Peripheral blood involvement by lymphoma was observed in 35.6% of cases with bone marrow involvement. We used WHO classification in the study for the bone marrow involvement of malignant lymphoma, and this single-institution study should give a useful, up-to-date histopathologic information.