Inv(14)(q11q32) in one of four different clones in a case of angioimmunoblastic lymphadenopathy

Angioimmunoblastic T-cell lymphoma

Angioimmunoblastic T-cell lymphoma (AITL) is a rare and aggressive neoplasm clinically characterized by sudden onset of constitutional symptoms, lymphadenopathy, hepatosplenomegaly, frequent autoimmune phenomena, particularly hemolytic anemia and thrombocytopenia, and polyclonal hypergammaglobulinemia. The lymph node histological picture is also distinctive, constituted by a polymorphic infiltrate, a marked proliferation of high endothelial venules, and a dense meshwork of dentritic cells. The neoplastic CD4+ T-cells represent a minority of the lymph node cell population; its detection is facilitated by the aberrant expression of CD10. Almost all cases arbor an EBV infected B-cell population. Patients with AITL have a poor prognosis with conventional treatment, with a median overall survival of less than 3 years. Patients achieving a good clinical response seem beneficiate from a consolidation with high-dose therapy and autologous stem cell transplantation. Constitutional symptoms and autoimmune phenomena, and some times also the neoplastic masses may respond to immunosuppressive or immunomodulatory agents such as thalidomide.

Stepwise development of chromosomal abnormalities in angioimmunoblastic lymphadenopathy

Cytogenetic studies of lymphoproliferative diseases, such as angioimmunoblastic lymphadenopathy (AILD), may provide a clue to the understanding of tumor development. Angioimmunoblastic lymphadenopathy may evolve from a nonmalignant lymphoproliferation into a peripheral T-cell lymphoma or even into a high-grade B-cell lymphoma and thus offers the chance to observe cytogenetic changes during lymphoma development. We report the cytogenetic findings in 24 cases of AILD. They are discussed together with 18 previously published cases from the same series. A striking feature was that unrelated chromosome abnormalities, both clonal and nonclonal, were frequently observed. Eighteen of 25 cases with aberrant clones show trisomy 3 (a characteristic chromosome abnormality in peripheral T-cell lymphoma), trisomy 5, or both. This finding provides cytogenetic evidence that these cases are definitely peripheral T-cell lymphomas. From the results of the 42 cases, hypotheses of stepwise evolution of the chromosome abnormalities in AILD are deduced: the first step is the appearance of chromosome abnormalities in different cells because of a genetic instability. At this time, clonal proliferation of T cells was already demonstrated by the rearrangement of T-cell receptor genes. As a second step, chromosomally aberrant clones become established. A cytogenetically detectable monoclonal proliferation represents the third step.

Inv(14) with distal breakpoint in 14q32.1 in three cases of T cell lymphoma

The distal breakpoint of inv(14) in T cell clones, established from patients with ataxia telangiectasia, lies outside the immunoglobulin heavy chain gene locus on 14q32.3, and more proximal to the centromere than the distal breakpoint of inv(14) in the T cell lymphoma cell line SUP-T1. We report 3 cases of T cell lymphoma cytogenetically showing the same type of inv(14) as the AT T cell clones. All 3 cases express a similar immunophenotype, which is that of peripheral T lymphocytes with phenotypic remnants of thymic or postthymic lymphoblasts. This finding provides evidence that this type of inv(14) is involved in the malignant transformation of mature T lymphocytes.