The International Working Group for Myeloproliferative Research and Treatment (IWG-MRT) has provided criteria for post-essential thrombocythemia myelofibrosis.
Required criteria:
(1) previous diagnosis of essential thrombocythemia by WHO criteria
(2) bone marrow fibrosis (Grade 2 or 3 on a 0 to 3 scale; Grade 3 or 4 on a 0 to 4 scale)
Additional criteria:
(1) anemia with >= 2 g/dL decreased from baseline hemoglobin level
(2) peripheral blood smear show leukoerythroblastic picture
(3) one or more constitutional findings (unexplained fever > 37.5°C; night sweats; > 10% weight loss in 6 months)
(4) increasing splenomegaly (either newly palpable splenomegaly OR >= 5 cm increase in palpable splenomegaly).
(5) increased serum LDH concentration
where:
• Palpable splenomegaly is measured as the distance from the tip of the spleen to the left costal margin.
The diagnosis of post-polycythemia vera myelofibrosis is made with:
(1) both require criteria
(2) 2 or more additional criteria
