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The Leukemia/Bone Marrow Transplant Program of BC

Hematology Dictionary
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M

Macroglobulinaemia
In certain conditions, such as Waldenstrom's Macroglobulinaemia, affected lymphocytes produce an excess amount of an abnormal antibody known as IgM for Macroglobulin.

Macrophage
A type of white blood cell which migrates from the blood into tissues and acts as a scavenger, ingesting particles such as bacteria.

Magnetic Resonance Imaging
A body scanning technique, which uses an intense magnetic field to generate images of the internal organs. Properties of normal and cancerous tissue differ, allowing malignant tumors to be visualized by computer processing of the signals detected.

Maintenance Treatment
Treatment given for a period of months or years to maintain remission and eliminate any residual leukemic cells in the body, usually for acute lymphoblastic leukemia.

Malignancy
A term applied to tumors characterized by the uncontrolled proliferation of cells. See also cancer.

Mast Cell Leukemia
The mast cell is related to the monocyte/macrophage cells of the immune system and is found in most tissues. Excessive production of mast cells may be seen in the conditions systemic mastocytosis and mast cell leukemia.

Megakaryocyte
Large cell in the bone marrow, which produce platelets.

Monoclonal
Proteins made by cells which all belong to the same clone are identical and are called monoclonal.

Monoclonal Antibodies
Antibodies made by cells belonging to a single clone. Current research is investigating their clinical application for targeted delivery of drugs to leukemic cells and to purify cells used for bone marrow and stem cell transplants.

Monoclonal Gammopathy Of Unknown Significance
Different types of gamma globulin are produced to deal with different infections. Exclusive production of one form of gamma globulin is called monoclonal gammopathy. If there is no evidence of disease such as myeloma or lymphoma to explain the presence of a monoclonal gammopathy it is called Monoclonal Gammopathy of Unknown Significance (MGUS).

Monocyte
A type of white blood cell of relatively large size, which acts as a scavenger and ingests large particles.

Monocytic Leukemia
Cancer of the blood due to proliferation of cells of the monocyte series.

Monosomy
Term, which indicates the loss of a whole chromosome.

MRC (Medical Research Council)
Government funded body "to promote the balanced development of medical and related biological research" in the UK. It organizes national clinical trials for the assessment of new treatment protocols for leukemia and some of the related diseases.

Mucositis
Inflammation of the mouth and throat, which may be caused by anti-leukemia drugs.

Multi-drug Resistance
Multi-drug resistance occurs when leukemia cells eliminate anti-cancer drugs before a high enough concentration to kill the cells is achieved. Resistance against most drugs will make the leukemia very difficult to treat.

Multiple Myeloma
A cancer caused by uncontrolled proliferation of the white blood cells called plasma cells within the bone marrow. The malignant cells do not usually accumulate in the blood and the tumor growth is restricted to the bones. This leads to bone destruction and is often associated with kidney problems.

Mutation
A minute genetic change to DNA, for example by exposure to hazardous chemicals or copying errors during cell division. If these affect normal cell function it can lead to disease development.

Myeloblastic
Immature cells of the myeloid series.

Myelodysplasia Or Myelodysplastic Syndromes (MDS)
A group of closely linked conditions in which the process of blood cell formation is disturbed by a failure of the immature cells to grow and develop normally. Sometimes referred to as "preleukemia", although only a minority of patients will ever develop leukemia. Treatment may be based on supportive therapy or involve the use of anti-cancer drugs.

Myelofibrosis
A disease in which the bone marrow is taken over by fibrous tissue and is no longer able to produce adequate numbers of mature blood cells. Often accompanied by enlargement of the spleen. It is occasionally found in cases of acute myeloid /acute lymphoid /chronic myeloid leukemia. The primary form is classified as a myeloproliferative disorder.

Myeloid
Collective term for the non-lymphocyte groups of white blood cells. It includes cells from the granulocyte, monocyte and platelets lineages.

Myelomonocytic
A condition, which affects both the myeloid and monocyte cells.

Myelopoiesis
The process of production and maturation of myeloid cells. See hematopoiesis.

Myeloproliferative Disorders
A group of disorders characterized by the over- production of blood cells by the bone marrow. One or more of the cell lineages may be involved and treatment varies according to the type and severity of the disease. See essential thrombocythaemia, polycythaemia rubra vera.

Myelosclerosis
See myelofibrosis.

 

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The information in this glossary is cited with permission from the Leukemia Research Foundation web site.

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