Bone marrow

           

      What is bone marrow?

            Bone marrow is a soft fatty tissue found inside the central spongy part of bones throughout the skeleton, and is the body's primary producer of white blood cells, red blood cells and platelets.

      

      

        

     It contains stem cells. The stem cells can develop into the red blood cells that carry oxygen through your body, the white blood cells that fight infections, and the platelets that help with blood clotting.

Bone Marrow Disorders

          A number of diseases or conditions can affect the structure and function of bone marrow. This in turn can affect the production and/or function of any of the mature blood cells or their immature precursors.

 The disorders may be due to 

1. The bone marrow is unable to produce one or more types of cells (e.g., aplastic anemia). 

• Insufficient amount of nutrients such as iron, vitamin B12, or folate, affects the bone marrow's ability to produce normal red blood cells; those produced may be small (microcytic), large (macrocytic), and/or may have decreased amounts of hemoglobin inside them (hypochromic).

2. White blood cells such as abnormal lymphocytes or plasma cells are overproduced (e.g., lymphomas, multiple myeloma).

3. Infection of the bone marrow can be caused by viruses, bacteria or fungi and can affect the production of cells.

4. One or more types of cells may begin to overproduce; this crowds out and decreases the production of the other cell types (e.g., polycythemia vera, essential thrombocythemia).

5. The bone marrow produces abnormal cells that don't mature or function properly (e.g., leukemias, myelodysplastic syndrome).

6. The supporting fibrous tissue network within the bone marrow increases and compresses the cells within the marrow, resulting in abnormally-shaped cells and low numbers of cells (e.g., myelofibrosis).

7. Cancer may spread from other parts of the body (metastasize) into the bone marrow, affecting cell production.

1. Myelodysplastic Syndromes (MDS) are a group of diseases caused by abnormal bone marrow cell production. 

• Frequently with MDS, the marrow appears to be making many blood cells, but they are defective and get destroyed before they can make it out into the blood (ineffective production). 

• This leads to symptoms of anemia, infection, and/or excessive bleeding and bruising. 

• MDSs are classified partially by how the cells in the bone marrow and in circulation look under the microscope and include:

 2. Anemia, low neutrophil count (neutropenia) and/or thrombocytopenia that do not respond to treatment (refractory), sometimes requiring one to received blood transfusions.

• Abnormal cell appearances (dysplasia) in one or more than one cell lines. Increase in immature precursors (blasts) in the marrow, with risk of developing to acute myeloid leukemia. 

3. Aplastic anemia – a defect in a stem cell or injury to the bone marrow results in the loss of cell precursors (usually the type that develops into RBCs).

• Some cases of aplastic anemias are caused by radiation or exposure to chemicals such as benzene or certain drugs. 

• A few are due to rare genetic abnormalities such as Fanconi anemia or associated with an acute viral illness such as human parvovirus.
• Anemias caused by nutritional deficiencies such as iron, folate, vitamin B12, chronic infection or inflammation, and/or hemoglobin abnormalities (hemoglobinopathies) that result in abnormally shapes or sizes of RBCs.
• Some types of anemia are caused by a deficiency or dysfunction of erythropoietin, a hormone produced by the kidneys that stimulates the bone marrow to produce RBCs. A lack of erythropoietin can lead to decreased red cell production by the bone marrow.

What Is Bone Marrow Cancer?

Bone marrow cancer happens when cells in the marrow begin to grow abnormally or at an accelerated rate. Cancer that starts in the bone marrow is called bone marrow cancer or blood cancer, not bone cancer.

         

Diagnosing bone marrow cancer

            If you have signs of bone marrow cancer, your doctor will review your medical history and do a complete physical examination. Depending on those findings and your symptoms, diagnostic testing may involve:

 

·       Blood tests, such as complete blood count, chemistry profile, and tumor markers

·       Urine tests to check protein levels and assess kidney function

·       Imaging studies such MRI, CT, PET, and X-ray to look for evidence of tumors

·       Biopsy of the bone marrow or enlarged lymph node to check for the presence of cancerous cells.

What Is a Bone Marrow Transplant?

• A bone marrow transplant is a medical procedure performed to replace bone marrow that has been damaged or destroyed by disease, infection, or chemotherapy.
• This procedure involves transplanting blood stem cells, which travel to the bone marrow where they produce new blood cells and promote growth of new marrow.