| Lymphoid leukemia | |
|---|---|
| Classification and external resources | |
| ICD-10 | C91 |
| ICD-9 | 204 |
| 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.
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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.
| 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 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.
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