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In the detection of haematological malignancy the purpose of detecting γδ T cells is to define particular T cell lymphomas, since αβ T cells strongly predominate in blood. Some care must be taken when small populations of γδ T cells are detected however, since these may arise in response to viral or other immune responses.

TCR analysis is not generally helpful in indicating T-cell clonality since around 95% express of circulating T cells express αβ chains; the remaining 5% of T cells have gamma γδ. in tissues this can be different since the γδ T cells are more abundant in skin and intraepithelial areas. The receptors also reflect different functions: αβ T cells behave as elements of the adaptive immune system while γδ cells have an innate immune function similar to NK cells.

• A predominant population of γδ T cells circulate may indicate a clonal proliferation most commonly will be hepatosplenic gamma-delta T-cell lymphoma or primary cutaneous t cell lymphoma (PTCL)