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Lymphocytic leukemia

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Lymphocytic leukemia

Lymphoid leukemia
Classification and external resources
ICD-10 9 MeSH D007945

Lymphoid leukemia or lymphocytic leukemia is a type of leukemia affecting circulating lymphocyte cells. This is in contrast to lymphoma, which is a solid tumor of the same type of cells.[1]

Lymphocytes are a subtype of white blood cells. Most lymphoid leukemias involve a particular subtype of lymphocytes, the B cell.

Classification

Historically, they have been most commonly divided by the stage of maturation at which the clonal (neoplastic) lymphoid population stopped maturing:

However, the influential WHO Classification (published in 2001) emphasized a greater emphasis on cell lineage. To this end, lymphoid leukemias can also be divided by the type of cells affected:

The most common type of lymphoid leukemia is B-cell chronic lymphocytic leukemia.

B-cell leukemias

Lymphoid leukemia
Classification and external resources
MeSH D015448

B-cell leukemia describes several different types of lymphoid leukemia 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[2] Small resting lymphocytes mixed with variable number of large activated cells. Lymph nodes are diffusely effaced[2] CD5, surface immunoglobulin[2] Occurs in older adults. Usually involves lymph nodes, bone marrow and spleen. Most patients have peripheral blood involvement. Indolent.[2]
Precursor B-cell lymphoblastic leukemia
(ICD-O: 9835/3-9836/3)
85% of acute leukemias in childhood,[2] Less common in adults[2] Lymphoblasts with irregular nuclear contours, condensed chromatin, small nucleoli and scant cytoplasm without granules.[2] TdT, CD19[2] Usually presents as acute leukemia[2]

Other types include (with ICD-O code):

T-cell leukemias

T-cell leukemia
Classification and external resources
MeSH D015458

T-cell leukemia describes several different types of lymphoid leukemias which affect T cells.

The most common T-cell leukemia is precursor T-cell lymphoblastic leukemia.[2] It causes 15% of acute leukemias in childhood, and also 40% of lymphomas in childhood.[2] It is most common in adolescent males.[2] Its morphology is identical to that of precursor B-cell lymphoblastic leukemia.[2] Cell markers include TdT, CD2, CD7.[2] It often presents as a mediastinal mass because of involvement of the thymus.[2] It is highly associated with NOTCH1 mutations.[2]

Other types include:

In practice, it can be hard to distinguish T-cell leukemia from T-cell lymphoma, and they are often grouped together.

References

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