Platelet aggregation and electron microscopic studies of platelets in preleukemia.

Platelet aggregation and electron microscopic studies of platelets were carried out at the time of diagnosis in 11 patients thought to have preleukemia. The clinical course confirmed the diagnosis of preleukemia in seven, of whom platelet aggregation had been performed in six and the results were abnormal in all. Electron microscopic studies were performed in six of the seven, and showed abnormal morphologic structure in five. One patient was unavailable for follow-up, and aplastic anemia developed in another. In time, two patients were seen to have nonmalignant blood disorders. Results of platelet aggregation studies were normal in both of these, but electron microscopy showed morphologic abnormalities. Platelet aggregation is useful in confirming the diagnosis of preleukemia. Electron microscopy of platelets is not so clearly helpful.