Abstract
Abnormal appearing cells having the superficial appearance of large lymphocytes were found in some cases of generalized malignant proliferations af the reticulum cell system and were studied by cytochemical methods and by phase microscopy. They were found to be very similar in their reactions to the "fixed" or tissue reticulum cells and in many respects to monocytes, but differed markedly from the cells of the lymphocytic system with which they are often confused. The term neoplastic lymphoid reticulum cell is applied to these cells since it indicates that they are malignant in nature and fundamentally of the reticulum cell type, although in fixed and stain material they may show some of the morphologic characteristics of the lymphocytic cells.