Reliability of Aspiration Biopsy in Thyroid Nodes: Study of 2190 Operated Patients

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Abstract
The cytologic finding was negative in 1841 patients; accurate in 1763 (95.8 %). Suspicious cytology proved malignant in 82 of 252 patients (32.5 %). Positive cytology was accurate in 88 out of 97 cases (90.7 %). In 1942 benign goiters, cytology was accurate in 90.8 % of patients, false suspicious in 8.7 % and false positive in 0.5 %; the highest percentage of misdiagnosis was in adenomas (15.8 %) and thyroiditis (19.0 %). In 248 malignant goiters, cytology was accurate in 35.5 % of patients, suspicious in 33.1 %, and false negative in 31.4 %. False-negative cytology was found in 44 % of follicular cancers, 22.2 % of papillary and medullary, and 12.9 % anaplastic. The most frequent false-negative cytologic diagnosis was the adenomatous goiter. The accuracy of cytology was statistically higher in papillary cancers than in follicular (77.8 % vs 56.0 %), in undifferentiated tumors than in differentiated (83.7 % vs 65.0 %), and in adenomatous nontoxic goiters than in adenomas, thyroiditis and toxic goiters (80.3 % vs 42.7 %), 20.1 % and 13.4 %). Positive preoperative fine needle aspiration biopsy cytology is a worthwhile and reliable finding; it fails in less than 10 % of patients. Negative cytology, however, does not exclude malignancy in thyroid nodes; it is false negative in more than 30 % of cancers.