USEFULNESS OF SURFACE PHENOTYPE STUDY OF INTRATHYROIDAL LYMPHOCYTES OBTAINED BY FINE-NEEDLE ASPIRATION CYTOLOGY IN AUTOIMMUNE THYROID-DISEASE AND MALIGNANT-LYMPHOMA OF THE THYROID

OBJECTIVES The surface phenotypes of intrathyroidal lymphocytes have b een studied in various thyroid diseases. In most of the previous repor ts, intrathyroidal lymphocytes were obtained by surgical operation. We evaluated the usefulness of surface phenotype study of intrathyroidal lymphocytes obtained by fine needle aspiration in the diagnosis of Gr aves' disease, chronic thyroiditis, and malignant lymphoma of the thyr oid. PATIENTS AND DESIGN Eighty-seven untreated patients including 24 with Graves' disease, 59 with chronic thyroiditis, and 4 with malignan t lymphoma of the thyroid, and 2 treated patients with malignant lymph oma of the thyroid were studied. Surface phenotypes of the peripheral lymphocytes and the intrathyroidal lymphocytes obtained by fine needle aspiration were analyzed using a FACScan and the monoclonal antibodie s: anti-Leu5b/CD2, Leu4/CD3, Leu3a/CD4, Leu2a/CD8, and Leu12/CD19. Per centages of cells positive for each monoclonal antibody were calculate d. In one case with malignant lymphoma, monoclonal antibodies to surfa ce-immunoglobulin markers were also studied. RESULTS In peripheral lym phocytes, the percentage of positive cells in each phenotype was almos t normal in each disease. In intrathyroidal lymphocytes, the percentag e of CD19 positive cells was increased, and the percentage of CD2 and CD3 positive cells was reduced compared to those of peripheral lymphoc ytes in each disease. The percentage of intrathyroidal CD19 positive c ells was remarkably high in malignant lymphoma, constituting more than 70% of cells. In Graves' disease, a relative decrease in the percenta ge of intrathyroidal CD4 positive cells and an increase in CD8 positiv e cells compared to peripheral lymphocytes were observed. In 2 treated patients with malignant lymphoma of the thyroid, the intrathyroidal C D19 positive cells almost disappeared in a patient shortly after succe ssful treatment, and reappeared to constitute 76% of cells in a patien t in relapse. In one case with malignant lymphoma in which monoclonal antibodies to surface-immunoglobulin markers were studied, the clonali ty of the affected cells could be demonstrated; more than 70% of the c ells were positive for kappa light-chain and mu and delta heavy-chain. This finding was proved by subsequent immunohistochemical study based on open biopsy. CONCLUSIONS Surface phenotype study of intra-thyroid lymphocytes obtained by fine needle aspiration has limited utility in the evaluation or diagnosis of Graves' disease and chronic thyroiditis . However, this simple rapid method is very helpful in the diagnosis a nd follow up of malignant lymphoma of the thyroid.