(a) A bone marrow leukemic cell in patient no. 1 at diagnosis containing abundant abnormally shaped primary granules, including Auer rods and Chediak-Higashi–type inclusions. Dilatation of rER is remarkable. (Original magnification × 10,800.) (b) Higher magnification of a cytoplasmic inclusion body of another cell in patient no. 1 that is membrane-bound and contains bundles of filamentous structures, similar to Auer rods. (Original magnification × 25,800.)