Myelofibrosis: causes, symptoms, diagnosis, treatment

Myelofibrosis (idiopathic myeloid metaplasia, myelofibrosis with myeloid metaplasia) is a chronic and usually idiopathic disease that is characterized by bone marrow fibrosis, splenomegaly and anemia with the presence of immature and drop-shaped erythrocytes. For the diagnosis, it is necessary to study the bone marrow and exclude other causes that can cause secondary myelofibrosis. Usually, supportive care is provided.

[1], [2], [3]

Epidemiology

The peak incidence of idiopathic myelofibrosis falls on the age between 50 and 70 years.

[4], [5]

Causes of the myelofibrosis

Myelofibrosis is characterized by fibroblast degeneration of the bone marrow with the loss of hematopoietic cells and the subsequent development of extramedullary hemopoiesis (mainly in the liver and spleen, the dimensions of which increase significantly). This pathology is usually a primary disease, which is probably due to the neoplastic transformation of the multipotent stem cells of the bone marrow - these stem cells stimulate bone marrow fibroblasts (this process is not part of neoplastic transformation) to increased collagen formation. Myelofibrosis can also occur due to various hematologic, oncological and infectious diseases. In addition, myelofibrosis can be a complication of chronic myelogenous leukemia and occurs in 15-30% of patients with true polycythemia and a prolonged course of the disease. A large number of immature erythrocytes and granulocytes enter the bloodstream (leucoerythroblastosis), which may be accompanied by an increase in LDH activity of the blood. In the outcome of myelofibrosis, there is a failure of bone marrow hematopoiesis with the development of anemia and thrombocytopenia. A rare variant of this disease is malignant or acute myelofibrosis, which is charasterized by faster progression; it is possible that this form of the disease is in fact true megakaryocytic leukemia.

Conditions associated with myelofibrosis

Condition	Example
Malignant diseases	Leukemia, true polycythemia, multiple myeloma, Hodgkin's lymphoma (Hodgkin's disease), non-Hodgkin's lymphomas, cancer with metastatic bone marrow disease
Infections	Tuberculosis, osteomyelitis
Toxins	X-ray or y-radiation, benzene, thorium dioxide
Autoimmune diseases (rare)	Hard currency

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Symptoms of the myelofibrosis

Early stages can be asymptomatic. Splenomegaly may be observed; at later stages, patients may complain of general malaise, weight loss, fever, and spleen infarcts may also be detected. 50% of patients have hepatomegaly. Sometimes lymphadenopathy is detected, but this symptom is not typical for this disease. Approximately 10% of patients develop fast-progressive acute leukemia.

Diagnostics of the myelofibrosis

Idiopathic myelofibrosis should be suspected in patients with splenomegaly, spleen infarction, anemia, or an unexplained increase in LDH levels. If you suspect a disease, you need to perform a general clinical blood test and conduct a morphological study of peripheral blood and bone marrow with a cyto-genetic analysis. It is necessary to exclude other diseases associated with myelofibrosis (eg, chronic infections, granulomatous diseases, cancer metastases, hairy cell leukemia, autoimmune diseases); for this, bone marrow research is usually performed (with appropriate clinical and laboratory data).

Blood cells have a different morphological structure. Anemia is a characteristic sign of the disease and tends to progress. Erythrocytes are normochromic-normocytic with small poikilocytosis, in addition, reticulocytosis and polychromatophilia are observed. In the peripheral blood, nucleated erythrocytes can be found. In the late stages of the disease, erythrocytes are deformed, can take the form of a drop; These changes are enough to suspect the disease.

The level of leukocytes is usually elevated, but very variable. As a rule, immature neutrophils are found, blast forms can be present (even in the absence of acute leukemia). At the onset of the disease, the platelet count may be high, normal, or decreased; with the progression of the disease there is a tendency to thrombocytopenia. In the peripheral blood, the level of progenitor cells may increase (as detected by counting the number of CD34 + cells).

Aspiration of the bone marrow is usually dry. Since confirmation of the diagnosis requires the detection of bone marrow fibrosis, and fibrosis can be distributed unevenly, then when receiving an uninformative first biopsy, it must be repeated elsewhere.

[7], [8], [9], [10]

Treatment of the myelofibrosis

To date, there is no treatment that initiates the reverse process or gives effective control over the disease. Therapy is aimed at eliminating symptoms and treating complications.

Androgens, splenectomy, chemotherapy and radiotherapy on the spleen area are sometimes used to alleviate the condition of the patient. With a low level of erythropoietin (EPO), corresponding to the degree of anemia, therapy with erythropoietin at a dose of 40,000 units per subcutaneously once a week may sufficiently increase the hematocrit; otherwise, transfusions of erythrocyte mass are necessary. The problem of allogeneic bone marrow transplantation should be considered in young patients with advanced stages of the disease.

Forecast

The median survival from the onset of the disease is about 5 years, although in some cases the diagnosis can not be made immediately. The presence of general symptoms, anemia or certain cytogenetic abnormalities indicate a poor prognosis; In the presence of anemia and some cytogenetic disorders, the median survival may be reduced to 2 years.

[11], [12]