Comparison between preoperative cytology and intraoperative frozen-section biopsy in the diagnosis of thyroid nodules.

The value of intraoperative frozen-section biopsy of thyroid nodules (solitary or dominant in a multinodular goitre) was examined in patients who underwent fine-needle aspiration cytology (FNAC) for diagnosis before operation. A total of 170 consecutive patients were evaluated and classified according to whether the cytological diagnosis was benign, suspicious or malignant. In the benign group, diagnostic accuracy was 98 per cent for FNAC and 97 per cent for intraoperative biopsy. In those with suspicious cytology, diagnostic accuracy was 12 per cent for FNAC and 96 per cent for intraoperative biopsy. In those with malignant cytology there was 100 per cent accuracy for FNAC and 76 per cent for biopsy. Intraoperative biopsy by frozen section is useful in patients undergoing surgery for a thyroid nodule with a 'suspicious' cytology. It adds no information in patients with a diagnosis of malignancy following cytological assessment and is of limited use in those in whom a benign lesion is diagnosed.