​Myelofibrosis is a type of myeloproliferative neoplasms which is rare chronic blood cancers because of increased fibrosis or scarring in the bone marrow resulting in subnormal blood counts and an enlarged spleen. Myelofibrosis can happen on its own (primary myelofibrosis) or as a sequalae from another myeloproliferative neoplasm like polycythemia vera or essential thrombocythemia (secondary myelofibrosis.

​Myelofibrosis occurs when there is a mutation in genes which are involved in the regulation of blood cell production. Specific mutations include JAK2, Calreticulin and MPN gene mutations. The cause of the gene mutation is unknown and is usually not an inheritable mutation. 

​To make a diagnosis of myelofibrosis, a bone marrow aspiration and trephine biopsy is done to evaluate the degree of fibrosis.  Sample from the blood or bone marrow samples may be used to evaluate for gene mutations. This helps to confirm the diagnosis and also give more information regarding the prognosis and guide treatment options. 

Issues in patients with myelofibrosis include: