[A case of primary thyroid T-cell lymphoma with infiltration of lymphoma cells in peripheral blood: diagnosed by DNA analysis].

A 57-year-old woman came to our hospital with complaints of neck swelling and headache in 1991. She was diagnosed as having chronic thyroiditis in euthyroidism because she had a diffuse goiter with both antithyroglobulin antibody (TGHA) and antimicrosomal antibody (MCHA). In 1992, she complained of the rapid growth of her thyroid gland and a swallowing disturbance. Atypical lymphocytes were observed in 16.5% of leukocytes in peripheral blood and similar atypical cells were found in bone marrow. Although an ultrasound scan of the thyroid gland revealed a symmetrical enlargement without a pseudocystic appearance, cytological study with fine needle aspiration biopsy of the thyroid gland demonstrated an abundance of atypical lymphoid cells. A whole body scintigram with 67gallium citrate showed no significant accumulation except in the thyroid gland. With a diagnosis of suspected primary thyroid lymphoma, total thyroidectomy was performed. However the diagnosis of malignant lymphoma was not confirmed histologically. A study of lymphocytes subset with two-color flow cytometry, which was performed for both lymphocytes in peripheral blood and infiltrating lymphocytes in the resected thyroid gland, revealed abnormal increased CD4 positive T cells and decreased HLA-DR expression. Additionally, southern blot DNA analysis for abnormal lymphocytes using restriction enzymes, EcoRI and BamHI, demonstrated rearrangement of the T-cell antigen receptor, which indicates a monoclonal proliferation of lymphocytes. After total thyroidectomy, atypical lymphocytes in peripheral blood decreased, and circulating autoantibodies including TGHA and MCHA disappeared. From these data, this patient was finally diagnosed as having a primary T-cell lymphoma of the thyroid gland, which is a very rare type of thyroid lymphoma.(ABSTRACT TRUNCATED AT 250 WORDS)