Primary myelofibrosis

ICD-O-3 Morphology
9961/3: Myelosclerosis with myeloid metaplasia
Effective 2001 and later
for cases diagnosed 2001 and later
Primary Site(s)
Primary site must be bone marrow (C421)

Not Applicable
Module Rule
Alternate Names
Chronic granulocytic-megakaryocytic myelosis
Megakaryocytic myelosclerosis
Myelosclerosis with myeloid metaplasia
Prefibrotic primary myelofibrosis
PMF is a disorder of the bone marrow in which the marrow is replaced by fibrous tissue. This is a clonal myeloproliferative disease which is characterized by a proliferation of mainly megakaryocytic and granulocytic elements in bone marrow. It is associated with reactive deposition of bone marrow connective tissue and with extra-medullary hematopoiesis (EMH).

Primary myelofibrosis begins with a hypercellular marrow with absence of overt fibrosis and often with early increase in reticulin fibers. This is call the "prefibrotic" stage of primary myelofibrosis.
Abstractor Notes
Primary myelofibrosis is a rare bone marrow disorder characterized by abnormalities in blood cell production and progressive scarring of the bone marrow. Blood forms in sites other than bone marrow such as liver and spleen. The blood and bone marrow are always involved.

About 50% exhibit JAK2 gene mutation, but the test is not specific enough to provide a definitive diagnosis. This disease is diagnosed clinically (a diagnosis of exclusion). The physician correlates information from JAK2 (if available), the equivocal results of the bone marrow and blood work with the clinical symptoms to arrive at a diagnosis of primary myelofibrosis.

In the early stages of disease, CD34 may be slightly increased in the bone marrow but not in the peripheral blood. In the later stages CD34 will appear in large numbers. This is peculiar to Primary myelofibrosis and does not occur in Polycythemia vera or Essential thrombocythemia.

Blood transfusions are given to correct anemia and should not be listed as treatment. Splenectomy may be done if the patient is symptomatic

Aspirin was previously documented as treatment for this disease. This was found to be incorrect. Treatment has been updated based on the NCI website (updated 6/12/15).
Definitive Diagnostic Methods
Clinical diagnosis
Genetic testing
Genetics Data
Janus kinase-2, JAK2
Radiation (for enlarged spleen)
Stem cell transplant
Surgery (splenectomy for enlarged spleen)
Transformations from
Corresponding ICD-9 Codes
238.76 Myelofibrosis with myeloid metaplasia
Corresponding ICD-10 Codes
D47.1 Chronic myeloproliferative disease
Corresponding ICD-10-CM Codes (U.S. only)
D47.4 Osteomyelofibrosis (effective October 01, 2015)
Signs and Symptoms
Bone pain
Early satiety
Night sweats
Weight loss
Progression and Transformation
Epidemiology and Mortality
Age: 60-70's years median age
Incidence: 0.5-1.5 per 100,000 persons per year
Sex: no male or female predominance
Survival: 3-7 years for patients diagnosed in fibrotic stage; 10-15 years for patients diagnosed in early prefibrotic phase