Identification of dysplasia in >10% of a particular hematologic lineage is an important defining criteria for myelodysplasia (MDS) in a bone marrow specimen. The following are the described agreed upon features of dysplasia per the WHO Classification.
Erythrodysplasia (Dyserythropoiesis)
- Nuclear
- Nuclear budding
- Internuclear bridging
- Karyorrhexis
- Multinucleation
- Cytoplasmic
- Ring sideroblasts (≥15% are considered to define significant dysplasia)
- Vaculoizaiton
- PAS positivity (diffuse or granular)
Megaloblastoid change is NOT specific individually for dysplasia, although it is often present in MDS. In the author’s opinion, megalobalstoid change (that is not significant) is poorly reproducible.
Granulocytic Dysplasia (Dysgranulopoiesis)
- Hypo- or Hyper-segmentation
- Hypogranularity (cytoplasmic)
- Pseudo-Chediak-Higashi granules (and small size)s
Hypogranularity of the cytoplasm can be difficult to accurately interpret if the aspirate smears are not of high quality.
Megakaryocyte Dysplasia (Dysmegakaryopoiesis)
- Micromegakaryocytes
- Non-lobated Nuclei
- Multiple widely-spaced nuclei (limited specificity unless the nuclei are rounded and similar in size)
CD61 is very helpful to identify micromegakaryocytes, which can easily be overlooked. See the CD61 section for more information.
References
Swerdlow SH, Campo E, Harris, NL, Jaffe ES, Pileri SA, Stein H, Thiele J (Eds): WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (Revised 4th edition). IARC: Lyon 2017