Department of Surgery, Shinshu University School of Medicine
Microcarcinoma of Thyroid, Ultrasonogram, Pathology of Thyroid
Twenty-nine thyroid nodules under 10 mm in diameter detected by ultrasonography in 26 patients were examined in this study. These nodules
were operated on after being diagnosed as microcarcinoma and the patients were followed-up with ultrasonograms for more than one year.
Ultrasonographic patterns of the nodules were classified into three types: Type I included masses with a high echogenic dot and an acoustic
shadow, Type IIa included masses with high echogenic dots surrounded by low level echoes and sharply defined boundaries Type IIb included
masses with an acoustic shadow and the same echogenic dots as Type IIa, and Type III included high echogenic dots surrounded by low level
echoes with irregular borders. Carcinoma was found in 33.3% of Type I, 50% of Type II, and 69.2% of Type III subjects. The histologic
classifications of microcarcinoma were 13 papillary and 2 medullary carcinomas. The ultrasonographic features were analyzed, comparing them
with histologic findings of the nodules, and were then evaluated from the view point of microcarcinoma diagnosis.