Surgical Pathology Criteria

Myelodysplastic Syndrome with Fibrosis

Differential Diagnosis

Hematolymphoid Disorders with Marrow Fibrosis (overview)

Disorder Distinguishing Feature(s)
Polycythemia Vera, Fibrotic Phase History of PV / JAK2+
Essential Thrombocythemia, Fibrotic Phase (rare) History of ET / may be JAK2+
CML, Fibrotic Phase History of CML / BCR-ABL1+
MDS with Fibrosis Dysplastic features in marrow
Acute Megakaryoblastic Leukemia Blasts, acute onset
Osteosclerotic Myeloma Plasma cells. light chain restricted
Acute Pan-myelosis with Myelofibrosis Bone pain, acute onset
Primary Myelofibrosis Clustered atypical megakaryocytic hyperplasia
Hairy cell leukemia Clonal B cells
MDS with Fibrosis = descriptive term that includes primary MDS (often RAEB2) with fibrosis and therapy related myeloid neoplasms with fibrosis

Primary Myelofibrosis, Fibrotic Phase MDS with Fibrosis Post-Polycythemia Vera Myelofibrosis
JAK2V617F mutations in 50% JAK2V617F mutations rare JAK2V617F mutations in almost 100%
Tightly clustered hyperchromatic megakaryocytes Increased but non-clustered dysplastic megakaryocytes Variable size and increase in megakaryocytes
Prominent splenomegaly Rare splenomegaly Prominent splenomegaly
Does not meet criteria for MDS or PV Commonly multilineage dysplasia and increased blasts History of polycythemia vera
Myelofibrosis grade 2-3 and cytogenetic abnormalities are common in all three

Non-neoplastic disorders especially associated with marrow fibrosis include HIV, autoimmune and congenital

Non-neoplastic disorders may simulate myelodysplasia

Myelodysplastic Syndromes

  Circulating Blasts Marrow Blasts Ring Sideroblasts Dysplastic Lineages Cytopenias
RCUD <1% <5% <15% Any 1 lineage 1 or 2
RARS 0 <5% ≥15% Only erythroid 1 or 2
RCMD <1% <5% Variable 2 or more lineages 1, 2 or 3
RAEB-1 <5% 5-9% Variable 1 or more 1, 2 or 3
RAEB-2 5-19% 10-19% or Auer rods Variable 1 or more 1, 2 or 3
del(5q) <1% <5% Variable Frequently hypolobated small megakaryocytes Usually 1 (anemia)


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