抄録
Electron microscopic study of two cases of Microgranular acute promyelocytic leukemia was performed. Leukemic cells of both cases had various ultrastructural characteristics which had been reported in cases of typical acute promyelocytic leukemia (APL), except for unusually small granules which measured 100 to 200 mμ in diameter. Among features characteristic for typical APL was there well-developed rough endoplasmic reticulum which was occasionally arranged in corollaceous pattern. There was also peculiar thread-like structure extending from granules and Auer rods. This structure formed circular or concentric profiles and had been reported as circular or concentric profiles of membrane bound dense material in previous literature. Both structures were positive for peroxidase reaction.
