Pseudo‐Chédiak–Higashi granules and other unusual cytoplasmic inclusions in refractory anaemia with excess blasts‐2

A 75-year-old man with a previous diagnosis of refractory anaemia with excess blasts type 1 (RAEB-1), with normal cytogenetic analysis, was hospitalised for worsening anaemia and increasing blast cells in the peripheral blood. Laboratory test showed a haemoglobin concentration of 74 g/l, platelet count 76 9 10/l and leucocyte count 17 67 9 10/l with 6% blast cells, 18% immature granulocytes and three nucleated red blood cells per 100 leucocytes. Macrocytosis and dysgranulopoiesis were present. A bone marrow film showed increased numbers of cells of neutrophil lineage, constituting more than 80% of cells, with dysgranulopoiesis and 13% blast cells. Dyserythropoiesis and dysmegakaryocytopoiesis were present. Molecular analysis showed that JAK2 V617F and BCR-ABL1 were absent and no mutation was detected in NPM1, CEBPA or FLT3. A diagnosis of RAEB-2 was made. Four different types of cytoplasmic inclusion were observed in a small percentage of blast cells and neutrophil precursors: (i) pseudo-Ch ediak–Higashi granules; (ii) less frequently, giant pseudo-Ch ediak–Higashi granules; (iii) azurophilic rectangular crystals, which in some instances were observed in transverse section suggesting a parallelepiped shape; and (iv) multilocular vacuoles (images). Rectangular crystals were also often present in mature neutrophils.