The platelet in leukemic reticuloendotheliosis. Functional and morphological evidence of a qualitative disorder.

Platelets were studied in a group of 10 patients with typical clinical course, morphological findings, and specific histochemical criteria for leukemic reticuloendotheliosis. In 8 of these, marked qualitative abnormalities were found. These included lack of aggregation following epinephrine stimulation (6 patients), and decreased platelet factor 3 availability following ADP stimulation (4 patients). In addition, platelets in 4 of the 10 patients were studied by electron microscopy. All had granular abnormality, and 1 case showed the presence of rough-surfaced endoplasmic reticulum. The functional and ultrastructural abnormalities of platelets reported here may be responsible for the clinically important bleeding episodes which were not attributable to thrombocytopenia in 2 of our patients. The findings also provide a clue to the basic nature of this histogenetically controversial malignancy.