Macrophage-histiocytes in malignant lymphoma, small lymphocytic type (well-differentiated lymphocytic lymphoma)

The authors studied the occurrence of Ricinus communis agglutinin (RCA)-binding macrophage-histiocytes in paraffin-embedded tumor tissue of 38 patients with malignant lymphoma, small lymphocytic type, a tumor of low-grade malignancy. Thirty-one patients (82%) had an indolent clinical course and were free of disease for a minimum follow-up period of 24 months. However, seven patients (18%) died within 24 months of biopsy, and six of the seven patients died of rapid progression of their tumor despite intensive treatment. Histologically, the tumors of these six short-term survivors were indistinguishable from those of the long-term survivors. RCA staining of paraffin-embedded tumor tissue of the 38 cases revealed three groups of tumors: (1) tumors with numerous (greater than 10/high-power field [HPF]) stromal macrophage-histiocytes (4 patients); (2) tumors with a moderate number (4-9/HPF) of macrophage-histiocytes (5 patients); (3) tumors with rare or no (0-3/HPF) macrophage-histiocytes, or only thin, anuclear variants (29 patients). Each of the six short-term survivors had readily demonstrable RCA-binding macrophage-histiocytes in their tumor; these were numerous in four and moderate in two. In contrast, macrophage-histiocytes were either rare or absent, or were anuclear variants, in 29 of the 31 patients who had an indolent clinical course. These observations suggest that in small lymphocytic type malignant lymphoma there is a subgroup characterized by an increased number of stromal macrophage-histiocytes and aggressive behavior of the tumor. Tumors of this subgroup can be detected by RCA staining.