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Leukemias: General Considerations And Clinical Classifications
A Leukemia Patient
Leukemias are a group of neoplastic disorders affecting mainly the leukopoietic tissues in the body and characterized by the presence of leucocytosis, immature leucocytes in the peripheral blood and proliferation of these immature cells in the bone marrow resulting in the suppression of normal tissue. The abnormal cells infiltrate several organs in the body. The exact cause for neoplastic transformation of the normal cell line is not known. The disease process starts in the bone marrow or lymphatic tissue depending on the cell type and the peripheral blood is flooded with abnormal cells at some stage of the disorder. Rarely the erythroid precursors, plasma cells or megakaryocytes may be involved.
Leukemias may be broadly grouped into acute and chronic leukemias. Acute leukemias affect younger age groups more frequently. They run a rapid course and the peripheral blood and bone marrow show the presence of large number of blast cells. If left untreated, these are fatal within weeks or months. Chronic leukemias generally affect the older age groups, they run a more protracted course and terminate life within 2-3 years of onset. Leukemias account for 0.15- 0.6% of the total medical admissions in many general hospitals in developing countries.
It is to be noted that chronic lymphatic leukemia is rare in developing countries when compared to the developed ones.
Classification of Leukemia
- Non-lymphoblastic (ANLL)
- M1- Acute myeloblastic (undifferentiated)
- M2- Acute myeloblastic (partly differentiated)
- M3- Acute promyelocytic (well differentiated)
- M4- Acute myelomonocytic
- M5- Acute monocytic
- M6- Erythroblastic (erythroleukemia).
- Acute lymphoblastic (ALL)
- L1- Small uniform cell type: 75% null cell types (common ALL or C.ALL)
- L2- More heterogenous cells: 25% T cell types (T. ALL)
- L3- Burkitt’s type of cells: rare, mostly B cell type (B. ALL).
- Chronic myeloid leukemia (CML)
- Chronic lymphatic leukemia (CLL)
- Hairy cell leukemia
- Prolymphocytic leukemia
- Plasma cell leukemia
- Chronic myelomonocytic leukemia
- Sezary syndrome (Leukemic phase of mycosis fungoides).
Ill defined groups
- Dysmyelopoietic syndromes
- Refractory anemia with excess blasts (RAEB)
These are both considered as preleukemic conditions.
Promising Stem Cell Therapy For Leukemia Patients
Details on Leukemia classifications
Leukemias have been classified by several authors based on different criteria. At present, the French American British (FAB) classification is one of the accepted systems for acute leukemia. Acute lymphatic leukemia is classified on the basis of cell size, nuclear chromatin pattern, nuclear shape, nucleoli, amount and basophilia of cytoplasm, and extent of cytoplasmic vacuolization. Acute myeloid leukemia is classified on the degree of maturation and differentiated of the abnormal cell.
In addition to the clear cut picture of leukemias, other less well-defined entities have been recognized, which when followed up, may develop into leukemia after varying intervals. The dysmyelopoietic syndromes are characterized by ineffective erythropoiesis manifested by morphological abnormalities in the marrow such as incordinated maturation of cytoplasm and the nucleus, nuclear division without cytoplasmic division, and syncytium formation. Another group is the refractory anemia with excess blasts (RAEB) in which the marrow is hypercellular with myeloblasts and promyelocytes forming 10-30% of the total nucleated cells. On follow up, the proportion of myeloid precursors increase and the condition may develop into florid acute myeloid leukemia.
© 2014 Funom Theophilus Makama