What is myelofibrosis
Myelofibrosis is a type of blood cancer that belongs to the group of chronic myeloproliferative diseases. In it, fibrous tissue in the bone marrow replaces blood-producing cells, resulting in the production of abnormally shaped red blood cells, as well as anemia and an enlarged spleen. It is an uncommon disease.
In a normal, healthy bone marrow, cells called fibroblasts produce the fibrous tissue that supports blood-producing cells. When myelofibrosis occurs, this production is excessive and expels the blood-producing cells, and some of them migrate from the bone marrow to the spleen and liver.
The production of red blood cells decreases and the patient develops anemia. Many of these red blood cells are immature or misshapen, and varying amounts of platelets (which usually decrease) and immature white blood cells (which may increase or decrease) are also seen in the blood.
It is a disease that affects men and women equally and is more common in people over 50 years old, with an average age of 65 to 67 years at diagnosis. But it can appear at extremes of age, which range from newborns to individuals in their 90s.
Myelofibrosis is classified into two types:
- Primary myelofibrosis – is myelofibrosis that develops on its own, with no determined or known cause. It occurs predominantly in men between 50 and 70 years of age. About half of people with primary myelofibrosis have a mutation in the JAK2 gene, which controls enzymes involved in cell growth and immune response, while others have a mutation in the CALR gene, which is related to making proteins needed for proper cell function, or MPL gene, thrombopoietin receptor. But these mutations cannot be defined as the cause of the disease, as many patients do not have any of the three and they are not unique to myelofibrosis;
- Secondary myelofibrosis – is myelofibrosis resulting from the evolution of other diseases or disorders, especially those of the blood (hematologic), malignant or non-malignant. Among these diseases and disorders are chronic myeloid leukemia, polycythemia vera, essential thrombocythemia, multiple myeloma, Hodgkin’s lymphoma and non-Hodgkin’s lymphoma, cancer with bone marrow metastases, and myelodysplasia. It can also occur in people with tuberculosis, pulmonary hypertension, lupus, systemic sclerosis, and HIV infection.
In both cases, there is a risk of the disease progressing to acute myeloid leukemia or problems such as bleeding in the digestive system and the development of thromboembolic events.
Symptoms and signs of myelofibrosis
Many myelofibrosis patients are asymptomatic or take many years to experience symptoms. When signs of the disease appear, early or late, the most common are:
- Excessive and progressive tiredness with no apparent cause;
- Short breath;
- Shortness of breath;
- Discomfort on the left side of the abdomen, caused by swelling of the spleen;
- Appearance of purple spots on the skin;
- Night sweats;
- Frequent infections, caused by decreased immunity;
- Weight loss for no apparent reason;
- Bone and joint pain;
- General malaise.
Diagnosis of myelofibrosis
When suspecting the occurrence of myelofibrosis due to a set of symptoms, the specialist doctor asks for a complete blood count to start the investigation. It is possible to detect problems in the cell count, as well as anemia and deformed and/or immature red blood cells, which indicate the disease.
If there are changes, then a bone marrow biopsy is performed. In it, a small fragment of the hip bone is removed with a needle and examined. A search for genetic mutations may also be requested, looking for mutated JAK2, CALR or MPL genes.
From the result of the biopsy it is already possible to close the diagnosis. Genetic tests are performed to detail the characteristics of the disease, which is useful in defining the treatment.
The only treatment capable of definitively curing myelofibrosis is bone marrow transplantation, but it should only be considered if the patient is up to 65 years of age, has no other significant health problems, and the chance of survival is more than five years.
The other possible treatments act to control the disease and prevent the condition from getting worse, in addition to alleviating the discomfort caused by the symptoms. Medications are used to reduce the size of the spleen, to normalize the platelet count and to improve anemia.
Radiation therapy can also help shrink the spleen, but only temporarily and at the risk of causing low white blood cell counts and infections.
In rare cases, it may be necessary to remove the spleen, which is only indicated if all other measures have already been tried.
As primary myelofibrosis has no defined cause and secondary myelofibrosis is a consequence of the evolution of other diseases and disorders, there is no known way to prevent them.