Delta-T-lymphocytosis in a patient with thymoma

Th1/Th2 balance alteration in the clinical course of a patient with pure red cell aplasia and thymoma

Peripheral T helper subsets in a patient with acquired pure red cell aplasia (PRCA) and thymoma were analysed by flow cytometry. Thymectomy resulted in a transient but definite improvement in anaemia. A continuous remission was attained by cyclosporin A (CsA) therapy. The changes in Th1/Th2 ratios corresponded with the haematological changes. Specifically, Th2 type lymphocytes were dominant during a haemopoietic suppression and elevation of the Th1/Th2 ratio was concomitant with haematological improvement. These observations suggest that polarization of Th subsets to Th2, induced by clonally expanded (gammadelta-type) T cells in thymoma, are involved in the pathogenesis of PRCA.

Oligoclonal peripheral T-cell lymphocytosis as a result of aberrant T-cell development in a cortical thymoma

A 42-year-old man presented with a locally invasive cortical thymoma. Before chemotherapy was commenced 36 months after presentation, an unusual peripheral lymphocytosis of 19 x 10(9)/l had slowly developed over time. After the first course of chemotherapy, the lymphocytosis showed a sharp decline to normal absolute cell numbers and subsequently remained at normal levels. Currently, the patient is in stable partial remission and doing well. Immunophenotypic analysis showed a mature T-cell phenotype with 78% TcR-a beta and 16% TcR-gamma delta in the absence of an immature component. Pretreatment Southern blot analysis of peripheral blood mononuclear cells showed an oligoclonal pattern with 13-20 rearranged fragments of different intensity for the TcR beta-gene. TcR gamma also showed a pattern compatible with an oligoclonal proliferation. After treatment, after normalization of absolute blood counts, the distribution of T-cell subsets still showed a slightly aberrant pattern. Immunophenotypic analysis of a blood sample taken 6 months later, also at normal absolute cell counts, showed an increase of thymocytes as well as of mature T cells with a polyclonal pattern on Southern blot analysis. These findings may be interpreted as the result of aberrant positive and negative selection and development of thymocytes in the microenvironment of neoplastic thymic epithelial cells and clonal selection through continuous peripheral stimulation. Moreover, this case stresses the importance of integrated interpretation of clinical, morphological, immunophenotypical, and molecular data to gain insight in unusual clinical problems.

Pure red cell aplasia with thymona: evidence of T-cell clonal disorder

Pure red cell aplasia (PRCA) sometimes accompanies thymoma. Herein, we report a PRCA patient with thymoma with a clonal disorder of T cells. A 55-year-old man presented with anemia and anterior mediastinum tumor. The laboratory study revealed hemoglobin 8.2 g/dl; leukocytes 15.8 x 10(9)/L with 76.5% neutrophils, 20.0% lymphocytes, and reticulocytes 0.0%. Bone marrow aspirate smears and biopsy sections revealed normal myeloid and megakaryocyte differentiation and contained no erythroid precursors. We made the diagnosis of PRCA. The size of the lymphocytes was small without any granules in the cytoplasm. The surface marker of peripheral blood mononuclear cells demonstrated increased CD2+, CD3+, CD4-, and CD8+ populations. The mediastinal tumor was resected and a thymoma diagnosed. A monoclonal rearrangement of T-cell receptor (TCR)-beta-chain gene was found using Southern blot analysis of the mononuclear cells in both peripheral blood and thymoma. Treatment with prednisolone, thymectomy, and cyclophosphamide exerted no beneficial effect. After initiation of the Cyclosporin A therapy, the patient developed reticulocytosis. This PRCA case seems to present a neoplastic proliferation of CD8+ T cells in peripheral blood and thymus with a monoclonal rearrangement of the TCR-beta-chain gene.