Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 616

To make the diagnosis, a bone marrow aspirate and biopsy are required. An aspirate is necessary to evaluate morphology, quantify the number of myeloblasts, and assess for cytogenetic abnormalities. A core bone marrow biopsy is used to assess the bone marrow cellularity, which is typically hypercellular and indicative of ineffective hematopoiesis in the setting of peripheral cytopenias.

The morphological features of red cell precursors in the bone marrow aspirate include megaloblastic (asynchronous maturation of the nucleus and cytoplasm), binucleate or multinucleated cells, and ring sideroblasts. Ring sideroblasts are red cell precursors with iron‐laden mitochondria and are defined by the presence of five or more Prussian Blue‐staining iron granules encircling more than one‐third of the nucleus in more than 15% of the erythroblasts. Erythroid hyperplasia may also be prominent and is associated with ineffective erythropoiesis that is a hallmark of MDS.

Abnormalities in the myeloid series include a predominance of immature myeloid cells and hypogranulation and hypolobulation of the nucleus in mature granulocytes. A classic finding is the presence of pseudo‐Pelger–Huet cells, which are granulocytes with a bilobed nucleus in a pince‐nez configuration. A required feature in the bone marrow of MDS patients is the presence of >5% myeloblasts: the proportion of myeloblasts has both diagnostic and prognostic information and is important in differentiating AML from MDS.

The megakaryocytes may likewise be dysplastic and may have not only a quantitative but also a qualitative defect. In the bone marrow, the megakaryocytes may be small and hypolobulated.