Pathologic nature of cystic thyroid nodules selected for surgery by needle aspiration biopsy.

Sixty euthyroid patients with cystic hypofunctioning thyroid nodules were selected for operation by the criteria of evidence of needle aspiration of cyst fluid with malignant cytologic findings, suspicion of malignancy on the basis of recurrent cyst fluid formation after at least two aspirations, or incomplete decompression after aspiration. Other factors such as size (greater than 3 cm in diameter), history of radiation, and cervical lymphadenopathy were given weight. Radiation exposure occurred in 14% of patients. Surgical pathologic findings revealed malignancy in 32%, adenoma in 43%, and colloid nodule in 25%, with a total neoplasia rate of 75%. The types of malignant tumors included six papillary, six mixed, three follicular, and four Hurthle. Surgical treatment included 26 near total thyroidectomies, 34 partial thyroidectomies, and four neck dissections without major morbidity or deaths. Cytologic false-negative rates were 50% cancer, 50% Hurthle cell 50%, and 60% adenoma, even after nucleopore filtration, emphasizing the value of surgical selection on the basis of cyst response to aspiration. Cytologic false-positive rate in the colloid group was 6% and 25% for false (solid) positive for echography. Bloody fluid occurred in all types of lesions but was more common in the cancer group. Thyroid ultrasonography does not appear to be an important way to assess thyroid nodular disease and has been, in our estimation, superseded by needle aspiration cytology. It should be recognized that cystic thyroid nodules, when selected for operation on the basis of the above mentioned needle biopsy and clinical criteria, have the same frequency of neoplasia and cancer as solid hypofunctioning thyroid nodules. Hence, it is recommended that all cystic lesions of the thyroid gland be assessed in accordance with such criteria to exclude underlying cancer.