Intraoperative decision making in follicular lesions of the thyroid: is tumor size important?

Intraoperative decision making in treating follicular lesions of the thyroid remains controversial because there are no reliable preoperative or intraoperative factors predictive of malignancy. This study was undertaken to determine whether lesion size is a reliable factor that can be used to predict a final pathologic diagnosis of follicular carcinoma.

This was a retrospective, case-matched control study. One hundred consecutive patients with follicular carcinoma were matched by gender, age, and date of operation with 100 patients with follicular adenomas. Seventy-nine matched pairs had pure follicular lesions and 21 matched pairs had oxyphilic variants of follicular lesions. After confirming adequate matching, lesion size was compared between groups.

Regardless of whether all follicular lesions were analyzed or whether only pure follicular or oxyphilic variant lesions were compared, there was no significant difference in lesion size between the carcinoma and adenoma groups. The mean size of all follicular carcinomas was 31.5 +/- 1.7 mm and the mean size of all follicular adenomas was 30.8 +/- 1.5 mm (p = NS). When the proportions of the carcinoma and adenoma groups were indexed by five different size intervals and compared, there was again no significant difference in any category.

On the basis of this case-matched control study, the size of a follicular lesion cannot be used to predict a final diagnosis of follicular carcinoma and is of no value when making intraoperative decisions about the extent of thyroid resection.