Myelodysplastic syndromes
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Myelodysplastic syndromes, abbreviated MDS, can be thought of a pre-leukemia/pre-lymphoma.
They should not be confused with myeloproliferative neoplasms.
Overview
Lab findings
- +/-Anemia.
- +/-Neutropenia.
- +/-Thrombocytopenia.
Notes:
- MDS is usu. an incidental finding, i.e. it is asymptomatic.
Associations
Syndromes associated with MDS:[1]
- Fanconi syndrome.
- Diamond-blackfan syndrome.
- Shwachman-diamond syndrome.
Diagnostic criteria
All of the following:[1]
- At least 6 months + persistent.
- Dysplasia.
- Cytologic:
- Need >=10% abnormal.
- Cytogenetic.
- Cytologic:
- All other causes excluded.
- Blast percentage <20%.
- If >=20% = leukemia.
- Criteria blast percentage:
- Bone marrow: 500 nucleated cells - includes erythroblasts, plasma cells; excludes megakaryocytes.
- Peripheral blood: 200 leukocytes.
Required clinical information
- CBC - usu. macrocytic anemia.
- Rx - may be Rx effect.
- Peripheral blood film.
- Clinical history (symptoms/presentation/PMHx).
Laboratory work-up
- H&E stain.
- Giemsa/Wright stain.
- Iron stain.
- Gomori silver stain.
DDx of MDS
- Nutritional deficiency.
- Vitamin B12.
- Folate.
- Toxic exposures.
- Rx.
- G-CSF.
- Biologic agents.
- Heavy metals.
- Chemotherapy.
- Rx.
- Infections.
- Parovirus B19.
- Other.
- Paroxysmal nocturnal hemoglobinuria (PNH).[2] (???)
- Congenital hematopoietic disorder.
- Congenital dyserythropoietic anemia.
Bone marrow specimens
Normal
- Age (years) ~ percentage of fat.
- Example 80 years old has ~ 80% fat in marrow space.
Erythroblasts:
- Typically away from bone.
Megakaryocytes:
- Alone - not in clusters.
- Not close to bone.
Myeloid cells:
- Adjacent to bone.
Histologic features
- Auer rods - used to be diagnostic of MDS regardless of blast count.
Dyserythropoiesis
- Abnormal RBC formation.
Histology
Nuclear
Features:[1]
- Nuclear budding.
- Intranuclear bridging (nuclei fail to separate post-division).
- Multinucleation.
- Megablastoid change.
- May be hard to see.
- Karyorrhexis (nuclear fragmentation).
Cytoplasmic
Features:[1]
- Ring sideroblasts.
- Rim of RBC has ring of iron.
- Vacuolization.
Dysgranulopoiesis
- Abnormal granulocyte formation.
Histology
Features:[1]
- Nuclear hypolobation (pseudo Pelger-Huët).
- Hypersegmentation.
- May be seen in vitamin B12 deficiency, Rx.
- Cytoplasmic hypogranulation.
- Pseudo-Chediak-Higashi granules.
- Small size.
Dysmegakaryocytopoiesis
- Abnormal megakaryocyte formation.
Histology
Features:[1]
- Micromegakaryoctes with hypolobated nuclei.
- Non-lobated nuclei of any size.
- Multiple widely separated nuclear lobes.
Image:
IHC
Typical IHC in work-up of MDS:
- CD34 - (myeloid) progenitor/precursor cells.
- CD117 - (myeloid) progenitor/precursor cells, mast cells.
- Tryptase - mast cells, immature basophils.
- Uncommonly done.
- CD61 - megakaryocytes.
- CD42b - megakaryocytes.
- CD20 - B cells.
- CD3 - T cells.
- Glycophorin A - erythroid cells.
- Glycophorin C - erythroid cells.
Notes:
- Other markers:
- Factor VIII.
- vWF.
- Blasts - the gold standard: histomorphology.
- Most blasts are CD34 +ve.
- Flow cytometry not useful (yet) for MDS -- as CD34 +ve != blast; may change with more multiplexing.
- CD117 marks some blasts that are CD34 -ve.
- Most blasts are CD34 +ve.
Cytogenetics
- Important in the Dx and prognostication of MDS; however, only ~50% have a cytogenetic abnormality based on karyotyping.
Common changes:
- Isolated del(5q).
- Isolated del(17p).
- Assoc. with pseudo-Pelger-Huet. (???)
- Monosomy 7.
- Monosomy 8.
There is a scoring system for cytogenetic abnormalities International Prognostic Scoring System,[3] abbreviated IPSS:
- Higher score = worse outcome.
WHO classification (2008)
- Refractory cytopenia with unilineage dysplasia (RCUD).
- Anemia.
- Neutropenia
- Thrombocytopenia.
- Refractory anemia with ringed sideroblasts (RARS).
- Refractory cytopenia with multilineage dysplasia (RCMD).[4]
- Refractory anemia with excess blasts (RAEB).
- RAEB-1.
- RAEB-2: Auer rods or >= 10% blasts.
- MDS with isolated del(5q).
- MDS unclassifiable.
See also
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 D. Good. 21 March 2011.
- ↑ URL: http://emedicine.medscape.com/article/207468-overview. Accessed on: 29 May 2011.
- ↑ Garcia-Manero, G. (Jun 2011). "Myelodysplastic syndromes: 2011 update on diagnosis, risk-stratification, and management.". Am J Hematol 86 (6): 490-8. doi:10.1002/ajh.22047. PMID 21594886.
- ↑ Rosati, S.; Mick, R.; Xu, F.; Stonys, E.; Le Beau, MM.; Larson, R.; Vardiman, JW. (Jan 1996). "Refractory cytopenia with multilineage dysplasia: further characterization of an 'unclassifiable' myelodysplastic syndrome.". Leukemia 10 (1): 20-6. PMID 8558932.