The pattern of bone marrow infiltration in non-Hodgkin's lymphomas.

The pattern of bone marrow infiltration in 40 consecutive cases of non-Hodgkin's lymphomas (NHLs) having marrow involvement is presented. For histological break-up, working formulation of NHLs was used. Low grade NHLs (50%) were the commonest, followed by intermediate (32.5%) and high grade NHLs (17.5%), respectively. Histologically, small lymphocytic type (32.5%) was the commonest, followed by diffuse small cleaved cell (15%) type; follicle small cleaved cell, diffuse mixed small and large cell as well as lymphoblastic types were equally frequent (12.5% each). Other histological types were less common. The pattern of infiltration of the bone marrow was diffuse in 76.7% of intermediate, 70% of low and 100% of high grade NHLs. It was focal random (non-paratrabecular) in 15% of low grade and 15.4% of intermediate grade NHLs. Focal paratrabecular pattern was evident in 15% of low grade and 7.7% of intermediate grade NHLs.