Diagnosis and classification of myelodysplastic syndromes (MDS) is based primarily on the morphological features of blood and bone marrow cells.1
Generally, bone marrow aspirate is removed by a physician in an out-patient setting and smears are prepared by a medical technician. A pathologist or hematologist then determines bone marrow morphology by examining at least 400 nucleated cells and 20 megakaryocytes.2
In healthy adults, a small percentage of cells will have dysplastic changes. The diagnosis of MDS requires a minimum of 10% dysplastic cells per lineage to distinguish it from minor dysplasia. In addition, dysplastic changes in at least 2 of the 3 hematopoietic cell lines should be seen. These include (Figure):3
Figure. Characteristic MDS bone marrow films.
A) Dysplastic large megakaryocyte with multiple separated nuclei and pseudo-Pelger cells.
B) Micromegakaryocyte and hypogranulated myelocytes.
C) Hypogranulated myelocytes and nuclear abnormalities of erythroblasts.
D) Dysplastic large megakaryocyte with multiple separated nuclei and hypogranulated myelocytes.
Courtesy of Ulrich Germing, University of DÃ¼sseldorf, Germany.
Hypercellularity is common due to active but ineffective erythropoiesis. Dyserythropoiesis can also manifest as abnormalities in the nucleus (budding, bridging, multinuclearity, megaloblastoid changes) and cytoplasm (vacuolation, abnormal hemoglobinization, basophilic stippling, ringed sideroblasts).
Perls staining is required to determine the presence and number of ringed sideroblasts (erythroid cells with iron deposition in the mitochondria).
The diagnosis of myelodysplastic syndromes requires a minimum of 10% dysplastic cells per lineage to distinguish it from minor dysplasia. In addition, dysplastic changes should be seen in at least 2 of the 3 hematopoietic cell lines.
Bone marrow trephine biopsy, a procedure that is also usually performed by a physician, is recommended to detect rare variants of MDS, such as fibrotic MDS and hypocellular MDS.1 Fibrotic MDS may be distinguished from myelofibrosis by the absence of splenomegaly and the presence of multilineage dysplasia. Hypocellular MDS can be distinguished from aplastic anemia by the presence of excess blasts (or CD34+ cells) and mild-to-moderate fibrosis.Learn more about bone marrow biopsy >
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