Immunophenotypic and Gene Rearrangement Analysis in Null- or T-Cell Neoplasias: Study of 16 Cases

Immunophenotypic and molecular studies were performed in sixteen cases of T-cell lymphoproliferative disorders. These included eleven patients with peripheral T-cell lymphoma, two thymic lymphomas and three patients with T-gamma lymphocytosis. Peripheral T-cell lymphomas were of both low and high grades. There was one case of Sezary's syndrome, two of small T-cell pleomorphic type, two medium sized T-cell pleomorphic lymphomas, two large T-cell pleomorphic type and four large cell anaplastic T cell lymphomas with activated T cell markers. Two patients had lymphoblastic lymphoma of thymic origin. In this report we attempted to correlate immunophenotypic and molecular characteristics. Rearrangements of the T-cell receptor (TCR) genes were observed in all cases, including those lacking any immunophenotypic markers, and unusual rearrangements of both the TCR and Ig genes were evident in thymic and peripheral T-cell lymphomas. In the cases of T-gamma lymphocytosis, a lymphoproliferative disorder that is not always clearly defined monoclonality was seen in one. The use of the genotypic approach for refining the characterization and diagnosis of some T-cell neoplasias is emphasized. The problems and pitfalls arising from the application of these methods are also discussed.