Primary myelofibrosis has a slow onset with symptoms appearing as the disease progresses. Symptoms noted are those commonly associated with all MPNs, including:
- Shortness of breath
- Unexplained weight loss
- Easy bruising or bleeding
- Night sweats
Splenomegaly due to extramedulary hematopoiesis is a common and important finding. Osteoschlerosis (increased bone density) may also occur. About one-third of patients are asymptomatic at presentation.
Hematologic findings in the peripheral blood include immature WBCs, immature RBCs, abnormal RBC morphology including anisocytosis and poikilocytosis, especially tear drop cells. The RBCs form normally, but take on an abnormal shape while squeezing through the fibrotic bone marrow and into the peripheral blood. Tear drop cells are indicated by the arrows in the image on the right. Bone marrow examination shows a normocellular or hypocellular marrow with moderate to marked fibrosis. Bone marrow aspiration may be unsuccessful ("dry tap") due to the increased amount of fibrous tissue, which blocks access to the sinusoidal blood within the bone marrow cavity.
Cytogenetic analysis confirms a positivity for the JAK2(V617F) mutation. The Philadelphia chromosome and the BCR/ABL translocation are not present.