Historically, they have been most commonly divided by the stage of maturation at which the clonal (neoplastic)<unk>  population stopped maturing: * Acute lymphoblastic leukemia * Chronic lymphocytic leukemia However, the influential WHO Classification (published in 2001) emphasized a greater emphasis on cell lineage. To this end,<unk> s can also be divided by the type of cells affected: * B-cell leukemia * T-cell leukemia * NK-cell leukemia The most common type of<unk>  is B-cell chronic lymphocytic leukemia. B-cell leukemias B-cell leukemia describes several different types of<unk>  which affect B cells. Comparison of most common B-cell leukemias Incidence Histopathology Cell markers Comments B-cell chronic lymphocytic leukemia (ICD-O: 9823/3) 30% of all leukemias. Also 3 to 4% of lymphomas in adults Small resting lymphocytes mixed with variable number of large activated cells. Lymph nodes are diffusely effaced CD5, surface immunoglobulin Occurs in older adults. Usually involves lymph nodes, bone marrow and spleen. Most patients have peripheral blood involvement. Indolent. Precursor B-cell lymphoblastic leukemia (ICD-O: 9835/3-9836/3) 85% of acute leukemias in childhood, Less common in adults Lymphoblasts with irregular nuclear contours, condensed chromatin, small nucleoli and scant cytoplasm without granules. TdT, CD19 Usually presents as acute leukemia Other types include (with ICD-O code): * 9826/3 – Acute lymphoblastic leukemia, mature B-cell type * 9833/3 – B-cell prolymphocytic leukemia * 9940/3 – Hairy cell leukemia T-cell leukemias T-cell leukemia describes several different types of<unk> s which affect T cells. The most common T-cell leukemia is precursor T-cell lymphoblastic leukemia. It causes 15% of acute leukemias in childhood, and also 40% of lymphomas in childhood. It is most common in adolescent males. Its morphology is identical to that of precursor B-cell lymphoblastic leukemia. Cell markers include TdT, CD2, CD7. It often presents as a mediastinal mass because of involvement of the thymus. It is highly associated with NOTCH1 mutations. Other types include: * Large granular lymphocytic leukemia * Adult T-cell leukemia/lymphoma * T-cell prolymphocytic leukemia In practice, it can be hard to distinguish T-cell leukemia from T-cell lymphoma, and they are often grouped together. NK cell leukemia Aggressive NK-cell leukemia (ANKL) is a<unk>  that is a deficiency NK cells. Not very much is known about this disease due to its rarity, but it is highly aggressive. Most patients will die within 2 years. Diagnosis The requirements for diagnosing ANKL are as follows: # Immature-looking NK cells # Certain immunophenotypes # Germline configuration genes: TCR-β and IgH # Restricted cytotoxicity The T-cell receptor (TCR) is an important factor when ANKL is being diagnosed along with T-cell leukemia. The TCR gene transcripts are normally positive for ANKL. Current Research is attempting to find the causation of ANKL. So far, the researchers have concluded that lineage of the T-cell receptor gene does not predict the behavior of the disease. Treatment ANKL is treated similarly to most B-cell lymphomas. Anthracycline-containing chemotherapy regimens are commonly offered as the initial therapy. Some patients may receive a stem cell transplant. Most patients will die 2 years after diagnosis.
Lymphoid leukemia
Myeloid leukemia
Prolymphocytic leukemia
B-cell leukemia
T-cell leukemia
Leukemoid reaction
Acute myeloid leukemia
Acute lymphoblastic leukemia