[Value of "non-specific" lymphoid infiltrates in bone marrow in high grade malignant peripheral non-Hodgkin's...

We studied iliac crest biopsies of 120 patients with extramedullary high-grade Non-Hodgkin's lymphomas (NHL). The bone marrow of 69 patients contained foci of small lymphoid cells, which cytologically differed significantly from the extramedullary NHL and which we termed abnormal lymphoid infiltrates (ALI). The ALIs in 14 out of 25 cases immunohistochemically investigated in more detail were made up of small CD3+ cells optionally intermingled with a minority of CD20+ cells of small to intermediate size. In 10 patients, however, the ALIs satisfied the criteria of a low-grade NHL. In the vicinity of the extramedullary high-grade lymphoma, residues of the corresponding low-grade NHL were identified in up to 7 of 10 cases. We conclude that bone marrow ALIs associated with extramedullary high-grade NHL exhibit at least in part the criteria of a systemic clonal expansion of premalignant lymphoid cells or low-grade NHLs respectively, which gives rise to the final evolution of the extramedullary high-grade NHL.