The majority of T-cells
Aberrant loss of expression may occur in T-cell lymphomas and may help to distinguish them from reactive T-cell proliferations2.
Expressed in 85% of T-ALL/T-LBL
3-10% of AML
Expressed by > 90% of B-CLL
almost all other low grade B cell lymphomas are CD5 negative.
some diffuse large B cell lymphomas are CD5-positive, possible associated with a worse prognosis.
Differentiation of T-cell lymphoma (CD5+) from NK cell lymphoma (CD5-), for example in nasal lymphomas5.
Pomplun found CD5 possibly useful in distinguishing thymic carcinomas from pulmonary carcinomas1. Several other studies have reported that CD5 is a promising marker for thymic carcinoma. Other epithelial neoplasms generally do not express this marker. Of note, the sensitivity and specificity depend on the clone of the anti-CD5 antibody: clone 54/F6 is less sensitive but more specific4.
References
1 S Pomplun. Immunohistochemical markers in the differentiation of thymic and pulmonary neoplasms. Abstract 158, Pathological Society of Great Britain and Ireland January 2001.
©SMUHT/PW Bishop