Incidence and histological features of bone marrow involvement in malignant lymphomas.

Bone marrow biopsy (BMB) is a routine investigation in the diagnosis and staging of Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL), and there is evidence supporting its prognostic importance in some histological varieties. The histological characteristics of BMB in 433 NHL and 155 HD patients were reviewed for clinicopathological correlations; 36 of these cases were also studied by means of immunohistochemistry. BM infiltrates were discovered in 171 NHL patients. In 36 cases, the diagnosis of NHL was directly established by BMB; a discordance between lymph node and BM histology was observed in 38 of the other 135 cases. BM-positive centroblastic and immunoblastic NHL were significantly associated with larger infiltrates, BM fibrosis, and megakaryocytic hyperplasia. Leukemization at diagnosis was more frequent in low-malignancy NHL. No correlation was found between histology and prognosis, although immunohistochemistry revealed a B-cell phenotype in all but two cases. BMB was positive in 18 of the 155 HD patients and directly diagnostic in two; Reed-Sternberg and Hodgkin cells were CD-30 positive and surrounded by T-cell infiltration. The concordance between BM and lymph node histology was fairly satisfactory, although the relationships between BM infiltration and other histological parameters may reflect peculiar interactions with BM microenvironmental factors. The usefulness of BMB in the diagnosis of malignant lymphomas has been demonstrated, and further progress can be expected from the availability of reliable immunohistochemical markers of clonality reacting on paraffin-embedded BM sections.