T-cell chronic lymphocytic leukemia. Unusual morphologic, phenotypic, and karyotypic features in association with light chain amyloidosis.
Lymphocytes that display a phenotype of mature B-cells, T-cells, natural killer (NK) cells, or a combination of T-cells and NK cells can be found in patients with lymphoproliferations that manifest as expansions of peripheral blood lymphocytes (PBL). If these PBL expansions exhibit clonality, they can be classified as chronic lymphocytic leukemia (CLL). A patient who had two simultaneous, clonal lymphoproliferative disorders manifested as an unusual T-cell CLL in conjunction with systemic light chain amyloidosis is described. Gene rearrangement studies of the PBL of the patient showed clonal rearrangements of both the T-cell receptor beta (T beta) chain and the immunoglobulin genes. Additional immunologic and microscopic studies of the T-cells of the patient showed that they were large, agranular, CD4+ T-cells that also expressed the NK cell marker CD57. Cytogenetics disclosed an unusual karyotype in the PBL. The pathogenesis of this T-cell CLL and whether it truly represents a malignant disorder, as well as its relation to amyloidosis, is discussed.