The unexpected thyroid cancer: surgical attitude.

A series of 18 patients with unexpected well-differentiated cancers of the thyroid is presented. This proved to be a high percentage of all patients operated for "benign" thyroid disease (6.5%), and a substantial percentage of all patients operated for thyroid cancer (44%). Preoperative investigations consisting mainly of thyroid function tests, ultrasound, scintigraphy, and fine needle aspiration biopsy, were not contributive for cancer. Intraoperative suspicion of malignancy induced extended surgery in one patient and frozen section biopsies in another 5 patients, with 3 positive answers resulting in immediate more radical operations. In 12 patients unsuspected cancer was diagnosed at paraffin section. This resulted in reoperation in 8 patients. Considering a number of arguments, we advocate a therapeutical guideline which makes a distinction between tumours which should be reoperated and tumours which are adequately treated by the initial resection.