(A1) Two neutrophils from a case of APL with CH-like granules. The promyelocytes looks normal in all parameters except in the primary granules. They are more abundant than normally seen; they are immature, different sized, and there is no dark purple of blue mature azure granules. The PMN looks normal except for increased number of primary (azure) immature granules. (B1) A promyelocyte from the same case of APL. Abundance of immature azure granules of different sizes. None of them mature and none are of abnormal sizes. There is one vacuole and the Golgi apparatus is clearly visible. (C1) Two promyelocytes similar to B1. Some azure granules undergo aggregation. (A2) Two promyelocytes in the same bone marrow smear. Split of maturational direction. One cell shows numerous Auer body–like inclusions and clear cytoplasm. The other shows numerous aggregates of azure granules. Some of them suggest fusion of smaller granules. (B2) Typical appearance of a bone marrow high-power field. Several leukemic promyelocytes. One shows Auer body–like inclusions. Others show immature azure granules at different levels of aggregation. The typical CH-like granules are not present. (C2) One large leukemic promyelocyte. A gigantic, pink, polygonal granule if formed. Many polygonal aggregates of small azure granules. Some clearing of cytoplasm (reduced total number of granules) can be seen. (A3) Fully developed CH-like granule in a leukemic promyelocyte. Other azure granules and, particularly, aggregates are not part of this granule. They follow their own development. Clearing of cytoplasm is also present. (B3) Several large and one gigantic, fully developed, pink-color and polygonal-shaped azure granules. Clear cytoplasm. This is a picture of a typical cell. (C3) A promyelocyte with three gigantic CH-like granules. All three are round, and all show structural changes. Onion- or myelin-like figures appear inside granules. They are apparently composed of the same material as other CH-like granules. Changes indicate hyalinization and autolysis. (A4) Two promyelocytes: one with Auer body–like inclusions, and the other with two small CH-like granules undergoing autolysis and one huge vacuole containing residual hyaline material of a CH-like granule, and a transparent, watery content. (B4) Two promyelocytes with gigantic, autolytic granules-vacuoles. Both resemble macrophages and phagocytosis. Only the presence of other azure granules in one of them suggest neutrophilic origin of this cell. (C4) A leukemic promyelocyte with many vacuoles. Few show some content. One (at 2 o’clock) is opened toward the cell exterior and some cytoplasmic ridges can be seen around the “rupture.” Two nucleoli identify the immaturity of the cell.