Usefulness of flow cytometry for differential diagnosis of precursor and peripheral T‐cell and NK‐cell lymphomas: Analysis of 490 cases

Although various CD markers have been analyzed in T-cell and natural killer (NK)-cell lymphomas, the sensitivity and specificity of these phenotypic features have not been satisfactorily characterized. Flow cytometry (FCM) was used to determine the phenotypic pattern of 490 T/NK-cell lymphomas with the aid of a set of surface antigens (CD2, CD3, CD4, CD5, CD7, CD8, CD10, CD11c, CD16, CD19, CD20, CD25, CD30, CD34, and CD56). In data obtained from 319 patients, CD10 expression was detected in 57% of angioimmunoblastic T-cell lymphomas, CD30 in 93% of anaplastic large cell lymphomas, CD34 in 50% of lymphoblastic lymphomas, and CD56 in 100% of extranodal NK/T-cell lymphomas nasal type. A total of 92% of adult T-cell leukemia/lymphomas (ATLL) had expression of CD25 and downregulation of CD7. Of special interest is that 92 ATLL (50%) were CD4+CD7-CD25+ phenotype while only four peripheral T-cell lymphoma unspecified (9%) and one (9%) cutaneous T-cell lymphoma had this phenotype. Phenotypic analysis using FCM was thus found to be useful for differential diagnosis of T-cell and NK-cell lymphomas.