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Fine-needle aspiration biopsies of thyroid nodules that are "nondiagnostic" do not exclude thyroid carcinoma

(March 2002)

The background of the study. Fine-needle aspiration biopsy is the best test to distinguish between malignant and benign thyroid nodules. However, from 5 to 20 percent of biopsy specimens are reported as nondiagnostic, because the specimen may contain only a few cells or the cells may be degenerating or otherwise unsuitable for analysis. This study was done to determine the outcome in patients who had a biopsy reported as nondiagnostic in a single year at the Mayo Clinic.

How the study was done. The records of all patients who had a fine-needle aspiration biopsy of a thyroid nodule reported as nondiagnostic in 1994 were reviewed in 2000. For the study, information was obtained about patient characteristics, results of repeat biopsies, surgical and pathologic findings, and follow-up to 2000 or to the last visit to the clinic.

The results of the study. During 1994, 937 biopsies of thyroid nodules were done, of which 182 (19 percent), done in 153 patients, were nondiagnostic. Sixty patients (39 percent) had a second biopsy; the cytology was benign in 30 (50 percent), suspicious in 5 (8 percent), malignant in 2 (3 percent), and nondiagnostic in 23 (38 percent). Ten of these 60 patients had surgery, of whom 6 had thyroid carcinoma. Among the 93 patients who did not have a second biopsy, 17 had surgery, and 4 had carcinoma. Overall, 10 patients (7 percent of the entire group and 37 percent of those who had surgery) had thyroid carcinoma.

Among the 126 patients (82 percent) who did not have surgery, 73 (58 percent) had one nondiagnostic biopsy, 23 (18 percent) had two nondiagnostic biopsies, and 30 (24 percent) had a second biopsy that revealed benign cells. Among the 52 patients followed for at least one year, 13 (25 percent) had resolution of thyroid disease, 23 (44 percent) had stable thyroid disease, 5 (10 percent) died of unrelated disease, and the status of 11 (21 percent) was not known.

The conclusions of the study. A substantial proportion of patients with thyroid nodules that are nondiagnostic on fine-needle aspiration biopsy prove to have thyroid carcinoma.

The original article. Chow LS, Gharib H, Goellner JR, van Heerden JA. Nondiagnostic thyroid fine-needle aspiration cytology: management dilemmas. Thyroid 2001;11:1147-51.