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Пульмонология, гематология (англ,рус)

 

Blood cells form in the bone marrow. Bone marrow is the soft material in the center of most bones.  Immature blood cells are called stem cells and blasts. Most blood cells mature in the bone marrow and then move into the blood vessels. Blood flowing through the blood vessels and heart is called the peripheral blood.

 

 

Blood & Lymphocyte Development

 

The bone marrow makes different types of blood cells.

 Each type has a special function:

nWhite blood cells help fight infection

nRed blood cells carry oxygen to tissues throughout the body

nPlatelets help form blood clots that control bleeding

 

Leukemia (or leukaemia) is a cancer of the blood or bone marrow characterized by an abnormal proliferation of blood cells, usually white blood cells (leukocytes). It is part of the broad group of diseases called hematological neoplasms.

Symptoms. Damage to the bone marrow, by way of displacing the normal marrow cells with increasing numbers of malignant cells, results in a lack of blood platelets, which are important in the blood clotting process. This means people with leukemia may become bruised, bleed excessively, or develop pinprick bleeds (petechiae). White blood cells, which are involved in fighting pathogens, may be suppressed or dysfunctional, putting the patient at the risk of developing infections.

Finally, the red blood cell deficiency leads to anemia, which may cause dyspnea. All symptoms may also be attributable to other diseases; for diagnosis, blood tests and a bone marrow biopsy are required.

Some other related symptoms:

Fever, chills, and other flu-like symptoms

Weakness and fatigue

Loss of appetite and/or weight

Swollen or bleeding gums

Neurological symptoms (headache)

Enlarged liver and spleen

 

Leukemia is clinically and pathologically split into its acute and chronic forms

nAcute leukemia is a rapidly progressing disease that affects mostly cells that are unformed or immature (not yet fully developed or differentiated). These immature cells cannot carry out their normal functions.

nAcute forms of leukemia can occur in children and young adults. (In fact, it is a more common cause of death for children than any other type of malignant disease.)

n Immediate treatment is required in acute leukemias due to the rapid progression and accumulation of the malignant cells, which then spill over into the bloodstream and spread to other organs of the body. If left untreated, the patient will die within months or weeks.

nChronic leukemia progresses slowly and permits the growth of greater numbers of more developed cells. In general, these more mature cells can carry out some of their normal functions. Typically taking months to years to progress, the cells are produced at a much higher rate than normal cells, resulting in many abnormal white blood cells in the blood. Chronic leukemia mostly occurs in older people, but can theoretically occur in any age group. Whereas acute leukemia must be treated immediately, chronic forms are sometimes monitored for some time before treatment to ensure maximum effectiveness of therapy.

 

Furthermore, the diseases are classified according to the type of abnormal cell found most in the blood.

When leukemia affects lymphoid cells (lymphocytes and plasma cells), it is called lymphocytic leukemia.

When myeloid cells (eosinophils, neutrophils, and basophils) are affected, the disease is called myeloid or myelogenous leukemia.

 

The major forms of leukemia are divided into four categories. The terms myelogenous or lymphocytic denote the cell type involved. Myelogenous and lymphocytic leukemia each have an acute or chronic form. Thus, the four major types of leukemia are acute or chronic myelogenous and acute or chronic lymphocytic leukemia.

 

Prevalence of the four major types

Acute lymphocytic leukemia (also known as Acute Lymphoblastic Leukemia, or ALL) is the most common type of leukemia in young children. This disease also affects adults, especially those age 65 and older

Acute myelogenous leukemia (also known as Acute Myeloid Leukemia, or AML) occurs more commonly in adults than in children. This type of leukemia was previously called acute nonlymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) most often affects adults over the age of 55. It sometimes occurs in younger adults, but it almost never affects children.

Chronic myelogenous leukemia (CML) occurs mainly in adults. A very small number of children also develop this disease.

The most common forms in adults are AML and CLL, whereas in children ALL is more prevalent

 

Leukemia.Causes and Risk Factors

There is no single known cause for all of the different types of leukemia. The different leukemias likely have different causes, and very little is certain about what causes them. Researchers have strong suspicions about four possible causes:

- natural or artificial ionizing radiation,

- certain kinds of chemicals,

- some viruses, and

- genetic predispositions.

Leukemia, like other cancers, result from somatic mutations in the DNA which activate oncogenes or deactivate tumor suppressor genes, and disrupt the regulation of cell death, differentiation or division. These mutations may occur spontaneously or as a result of exposure to radiation or carcinogenic substances and are likely to be influenced by genetic factors.

Viruses have also been linked to some forms of leukemia. For example, certain cases of ALL are associated with viral infections by either the human immunodeficiency virus (HIV, responsible for AIDS) or human T-lymphotropic virus (HTLV-1 and -2, causing adult T-cell leukemia/lymphoma).

Fanconi anemia is also a risk factor for developing acute myelogenous leukemia.

Until the cause or causes of leukemia are found, there is no way to prevent the disease.

 

Acute leukemia. Essentials of diagnosis.

nShort duration of symptoms, including fatigue, fever, and bleeding

nCytopenia or pancytopenia

nMore than 20 % blasts in the bone marrow

nBlasts in peripheral blood in 90 %

 

 

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