OBJECTIVETo evaluate pathomorphologic and immunohistochemical characteristics of the bone marrow involvement of lymphoma and its significance in the diagnosis and subtype of lymphoma with bone marrow involvement.

METHODSOne hundred and eighty eight formalin fixed and paraffin embedded bone marrow biopsy specimens were studied. Immunohistochemical staining was performed.

RESULTS(1) Five patterns of bone marrow involvement of lymphoma were found, including diffuse (44.9%), focal (29.3%), interstitial (11.6%) and nodular (6.1%). (2) There were many subtypes of lymphoma in these cases, the most common type was lymphoplasmacytic lymphoma (21.7%). (3) The lymphomas in bone marrow biopsy had their own special characteristics of morphology and immunophenotype as did in extra-medullar lymphomas. (4) Fibrosis (75.8%) and hematopoietic tissue hypoplasia (71.1%) were found in most cases and necrosis in a few cases.

CONCLUSIONSMost cases of bone marrow involvement of lymphoma could be diagnosed and classified by combination of histopathological and immunohistochemical analysis. Diagnosis of some cases could be made only after the review of pathological changes of lymph node. A few cases were difficult to classify their subtypes of lymphoma.