lymphoma incidence/prevalence measurement T-cell lymphoma incidence/prevalence measurement 2013-11-18T18:48:47Z Any measurement in which the number of individuals in a study population that display T-cell lymphomas at a point in time or develop T-cell lymphomas within a determined period of time are compared to the total number of individuals in the study population. Often expressed as a percentage but could be expressed as a ratio. T-cell lymphoma refers to a heterogeneous group of usually malignant lymphoid neoplasms that occur as circumscribed solid tumors and that are composed of T lymphocytes. T lymphocytes are white blood cells that complete maturation in the thymus and that have various roles in the immune system, including the identification of specific foreign antigens in the body, the mediation of cellular immune responses, and the activation and deactivation of other immune cells. CMO:0001909 JSmith clinical_measurement_ontology