**4. H&E and M-G staining**

Most pathologists are more familiar with H&E-stained samples than with M-G–stained samples in routine diagnostic work. As demonstrated in this study, H&E-stained specimens of BM, as well as M-G–stained samples, were available despite the difficulty in observation of granules in the cytoplasm in the myelocytic lineage. In this chapter, high-power magnification images are provided for understanding features of individual hematopoietic lineages for further clarifying morphological features of the subjects.

As demonstrated, H&E specimens allow the identification of myeloblasts. Therefore, the identification of "blasts" in H&E-stained sections should be clearly defined. In contrast to the M-G-stained sections, H&E-stained sections do show basophilic cytoplasm; rather, the transparency of the nucleus with one or more nucleoli is more identifiable as the feature of blasts in H&E staining. This phenomenon represents another feature of dysplasia with deformity in the shape with or without atypical morphological findings of the nucleus. In dysplasia, hyperlobulated or ring nuclei were observed, which is a diagnostic feature of dysmyelopoiesis. In addition, basophilic heterogeneity, exudation, or a "blot" in the erythroblast cytoplasm is identified in dysplasia. This basophilic exudation was clearer in H&E-stained specimens than in M-G-stained sections. In addition, H&E-stained clot samples are sufficiently useful for the observation of morphological changes and for the assessment of megakaryocytic features.

H&E-stained clot specimens are advantageous for diagnosing AML subtypes because they allow better identification of hematopoietic dysplastic cells than M-G–stained sections do. Pathologists can integrate findings from the three staining methods: H&E, M-G, and IHC: for the decisive diagnosis of AML subtypes. Routine histological observations using M-G or H&E staining will be more useful in combination with flow cytometry analysis for immunohistological assessment using anti-CD33 and anti-CD13, a set of antibodies used to accurately diagnose AML. Myelodysplasia is also identifiable by H&E staining. Using high magnification, such as 1000×, the blot and localized heterogeneous staining or budding of the nucleus is identifiable by H&E staining. In fact, this high-power magnification provides more cytological and histological findings for facilitating the diagnosis of MDS and MDS/MPN.
