STAINING FOR BCL-2 PROTEIN HELPS TO DISTINGUISH BENIGN FROM MALIGNANTLYMPHOID AGGREGATES IN BONE-MARROW BIOPSIES

Lymphoid nodules in a bone marrow biopsy may be either benign or malig nant. Morphological clues may help to differentiate the benign from th e malignant nodules. However, it is sometimes difficult, if not imposs ible, to make this distinction, especially in patients with a known lo w-grade lymphocytic malignancy. This study was undertaken to determine whether staining bone marrow biopsies with an antibody to the bcl-2 p rotein might aid in making this differentiation. Using a monoclonal an tibody to bcl-2, we stained 26 bone marrows with benign lymphoid aggre gates, 19 with a follicular lymphoma, 10 with small lymphocytic lympho ma/chronic lymphocytic leukemia, three with other non-Hodgkin's lympho mas, and three with other miscellaneous hematopoietic lesions. Only on e of the 26 benign lymphoid aggregates had moderate to intense stainin g with this antibody; in contrast, 79% of the follicular lymphomas sta ined positively. Eight of the 10 small lymphocytic lymphoma/chronic ly mphocytic leukemia cases stained with moderate to intense intensity; t he other two cases had weak staining. No consistent pattern was seen w ith the other six lesions. Based on this data, we conclude that lack o f staining of small lymphoid aggregates within the bone marrow with th e antibody to the bcl-2 protein is suggestive of a benign aggregate, w hereas moderate to strong staining intensity is most consistent with a malignant process.