- Increased serum level of lactate dehydrogenase.
- Palpable splenomegaly.
The median survival is 3.5 years to 5.5 years, but patients younger than 55 years have a median survival of 11 years.[3,4] The major causes of death include:
- Progressive marrow failure.
- Transformation to acute nonlymphoblastic leukemia.
- Thrombohemorrhagic events.
- Heart failure.
- Portal hypertension.
Fatal and nonfatal thrombosis was associated with age more than 60 years and JAK2 617V positivity in a multivariable analysis of 707 patients followed from 1973 to 2008. Bone marrow examination including cytogenetic testing may exclude other causes of myelophthisis, such as CML, myelodysplastic syndrome, metastatic cancer, lymphomas, and plasma cell disorders. In acute myelofibrosis, patients present with pancytopenia but no splenomegaly or peripheral blood myelophthisis. Peripheral blood or marrow monocytosis is suggestive for myelodysplasia in this setting.
There is no staging system for this disease.
Prognostic factors include:[8,9,10,11,12]
- Age 65 years or older.
- Anemia (hemoglobin <10 g/dL).
- Constitutional symptoms: fever, night sweats, or weight loss.
- Leukocytosis (WBC >25 × 109 /L).
- Circulating blasts of at least 1%.
Patients without any of the adverse features, excluding age, have a median survival of more than 10 to 15 years, but the presence of any two of the adverse features lowers the median survival to less than 4 years.[13,14] International prognostic scoring systems incorporate the aforementioned prognostic factors.[13,15]
Karyotype abnormalities can also affect prognosis. In a retrospective series, the 13q and 20q deletions and trisomy 9 correlated with improved survival and no leukemia transformation in comparison with the worse prognosis with trisomy 8, complex karyotype, -7/7q-, i(17q), inv(3), -5/5q-, 12p-, or 11q23 rearrangement.[7,16]
Asymptomatic low-risk patients (based on the aforementioned prognostic systems) should be followed with a watchful-waiting approach. The development of symptomatic anemia, marked leukocytosis, drenching night sweats, weight loss, fever, or symptomatic splenomegaly would warrant therapeutic intervention.
The profound anemia that develops in this disease usually requires red blood cell transfusion. Red blood cell survival is markedly decreased in some patients; this can sometimes be treated with glucocorticoids. Disease-associated anemia may occasionally respond to the following:[4,17,18,19]
- Erythropoietic growth factors. Erythropoietin and darbepoetin are less likely to help when patients are transfusion dependent or manifest a serum erythropoietin level greater than 125 U/L.[20,21]
- Prednisone (40–80 mg/day).
- Danazol (600 mg/day).
- Thalidomide (50 mg/day) ± prednisone. Patients on thalidomide require prophylaxis for avoiding thrombosis and careful monitoring for hematologic toxicity.
- Lenalidomide (10 mg/day) ± prednisone.[23,24,25] In the presence of del(5q), lenalidomide with or without prednisone, can reverse anemia and splenomegaly in most patients.[23,24,25] However, patients on lenalidomide require prophylaxis for avoiding thrombosis and careful monitoring for hematologic toxicity.
- Pomalidomide. Patients on pomalidomide require prophylaxis for avoiding thrombosis and careful monitoring for hematologic toxicity.