Use of fine-needle aspiration cytology and frozen section examination in diagnosis of thyroid nodules

Background: With the advent of fine-needle aspiration cytology (FNAC), the role of frozen section (FS) in the management of non-toxic thyroid nodules has become uncertain. Methods: During the period from January 1993 to December 1995, a total of 8 4 patients have undergone operative treatment for nontoxic thyroid nodules at the United Christian Hospital, Kowloon. The medical records of these pat ients were studied retrospectively. Results: In the benign group, the diagnostic accuracy of FNAC was 94% and t hat of FS was 91%. If FNAC reported malignancy, the diagnostic accuracy was 70%. If FS reported malignancy, the report was accurate in 100%. Among the 43 cases reported as benign on FNAC, FS did not alter the surgical managem ent in any case. In 10 cases reported as suspicious on FNAC, FS altered the surgical treatment in one (10%). However, among the 10 cases reported as m alignant on FNAC, FS subsequently altered the surgical management in five c ases (50%). In three cases of malignancy on FNAC, both FS and the final his topathology report showed benign disease. Hence, FS avoided overtreatment i n three patients. Conclusion: Frozen section is indicated if pre-operative FNAC of the thyroi d nodules suggests malignancy, in order to determine the extent of the oper ation and to avoid overtreatment of benign disease. However, FS can be omit ted if FNAC is reported as benign or suspicious.