Myelodysplastic syndromes

From Libre Pathology
Jump to: navigation, search

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]

  1. At least 6 months + persistent.
  2. Dysplasia.
    • Cytologic:
      • Need >=10% abnormal.
    • Cytogenetic.
  3. All other causes excluded.
  4. 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

  1. Nutritional deficiency.
    • Vitamin B12.
    • Folate.
  2. Toxic exposures.
    • Rx.
      • G-CSF.
    • Biologic agents.
    • Heavy metals.
    • Chemotherapy.
  3. Infections.
    • Parovirus B19.
  4. 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:

  1. Alone - not in clusters.
  2. 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.

Cytogenetics

  • Important in the Dx and prognostication of MDS; however, only ~50% have a cytogenetic abnormality based on karyotyping.

Common changes:

  1. Isolated del(5q).
  2. Isolated del(17p).
    • Assoc. with pseudo-Pelger-Huet. (???)
  3. Monosomy 7.
  4. 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).
    1. Anemia.
    2. Neutropenia
    3. 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. 1.0 1.1 1.2 1.3 1.4 1.5 D. Good. 21 March 2011.
  2. URL: http://emedicine.medscape.com/article/207468-overview. Accessed on: 29 May 2011.
  3. 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.
  4. 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.