Inflammatory and lymphoid lesions of the thyroid gland. Cytopathology by fine-needle aspiration.

The cytopathologic characteristics of the inflammatory and lymphoid thyroid lesions as seen in fine-needle aspirate smears of 103 patients are reviewed, with emphasis on pitfalls and association with other neoplasms. The cytologic diagnoses were as follows: subacute thyroiditis, 3; Hashimoto's thyroiditis (HT) with or without Hürthle cell nodule, 77; HT and Hürthle cell tumor, 2; HT and follicular neoplasm, 3; HT and papillary carcinoma, 5; lymphoma, 3; HT and nodular colloid goiter, 10. Fourteen patients were operated. Five erroneous diagnoses were uncovered; inexperience was the main reason for the mistakes. The greatest diagnostic difficulties are encountered in cases of Hürthle cell nodules and malignant lymphoma, but mistakes are likely to disappear after reasonable experience. Thyroid antibodies are of no help in sorting diagnostic problems, because a positive titer is only corroborative evidence of underlying HT and does not rule out an associated tumor. Conversely, a negative titer does not discard the diagnosis of HT. The association of nodular colloid goiter and HT is depicted. Problems of sampling and staining technic are discussed.