The validity of some morphologic methods in the diagnosis of thyroid malignancy.

The diagnostic accuracy of intraoperative frozen section and imprint cytology in thyroid conditions was analyzed along with that of cytofluorimetric nuclear DNA determination. Of 149 frozen sections in a four-year period, 90% gave a correct diagnosis, while four results were false-positive and one was false-negative. The intraoperative accuracy of imprint cytology was 95% in 309 examinations, with 12 false-positive and four false-negative results. The misjudgements with both morphologic methods derived mainly from decisions on benignancy or malignancy of follicular tumor types. Neither atypical adenoma nor encapsulated follicular carcinoma can be conclusively distinguished with these methods. Their routine application nevertheless is of great help to the surgeon, in that they can considerably reduce the need for second (radical) operations and thus the risk of complications. Nuclear DNA determination was unhelpful in the intraoperative situation.