Myelofibrosis is a rare cancer that affects your bone marrow, the spongy tissue inside some of your bones. In a healthy person, stem cells in the bone marrow make the red blood cells, white blood ...

which is a measure of red blood cells. With essential thrombocythemia, a CBC would show a high platelet count, and a blood smear may show clumps of platelets. Myelofibrosis may be diagnosed with a ...