Histopathological investigation of intranodular echogenic foci detected by thyroid ultrasonography.

OBJECTIVE: To determine the predictability of sonography for detection of calcifications in thyroid nodules by histopathologic examination and to demonstrate the association between calcification pattern and malignancy.

METHODS: We prospectively evaluated 81 dominant nodules from 81 patients. Thyroid glands were assessed preoperatively with thyroid ultrasonography, and the presence of sonographic calcification was specified as intranodular macro (coarse) and micro calcification. Micro and macro calcification in surgery specimens were specified postoperatively as present or absent in the histopathological evaluation. The correlation between sonographic and histopathologic calcifications and the relationship between malignancy and calcification patterns were determined.

RESULTS: Calcification was detected histopathologically in 66.7% of the sonographically calcified nodules and in 12.8% of the sonographically noncalcified nodules. The sensitivity and specificity of sonography for detecting histopathologic calcification were 84.8 and 70.8%, respectively, while positive and negative predictive values were 66.7 and 87.2%, respectively. The sonographical and histopathological outcomes for detection of macro and micro calcification showed 85 and 50% compatibility, respectively. The difference in malignancy rates between sonographic macro and micro calcified nodules was not significant (p=0.976). Histopathologic detection of calcification showed no significant difference between malignant and benign nodules (p=0.129).

CONCLUSION: Histopathology confirmed a high rate of sonographic macrocalcifications. The micro and macro patterns of sonographic calcification showed no particular association with thyroid malignancy. The preoperative risk of malignancy should be determined in conjunction with other known sonographic risk factors and diagnostic tests.