A quantitative study of histiocytic reticulum cells in diffuse and follicular non-Hodgkin's lymphomas.

Histiocytic reticulum cells have been counted in 160 lymph nodes, comprising 50 high grade non-Hodgkin's lymphomas, 90 lymphomas of low grade histology, and 20 specimens exhibiting reactive follicular hyperplasia. The histiocytes were shown immunohistochemically by virtue of their content of the cysteine proteinase cathepsin B. A consistent and striking finding was that high grade lymphomas contain many more histiocytes than low grade lymphomas. Immunoblastic neoplasms contain up to 24.2% of these cells, whereas low grade diffuse lymphomas possess only up to 3.6% histiocytes. Histiocytic reticulum cells were also counted in benign or malignant follicular lesions in standard areas from follicle centres only. No significant differences were found between low grade lymphomas and hyperplastic nodes. These findings are discussed in relation to previous, more limited studies.