Impact of Microcalcifications on Risk of Malignancy in Thyroid Nodules with Indeterminate or Benign Cytology

Objective Adverse sonographic features such as microcalcification may predict increased likelihood of malignant cytology by fine-needle aspiration and, accordingly, increased risk of malignant histology. Our objective was to study the predictive value of microcalcifications and other sonographic features for malignancy among thyroid nodules with benign or indeterminate cytology. Study Design Case series with chart review. Setting Academic teaching hospital. Subjects Patients (N = 769) with 858 thyroid nodules undergoing 1142 ultrasound fine-needle aspirations; 411 cases had surgical correlation. Methods Sonographic features predictive of malignancy were correlated with malignancy as determined by histology. Incidental malignancies occurring outside the index nodule were discounted. Results Cytology was inadequate (87 cases), benign (518), indeterminate (210), and malignant (44). In 32 cases, initial benign cytology was upgraded to a higher-risk category after repeat ultrasound fine-needle aspiration. Microcalcification (P =.001) and irregular margins (P =.04) were significantly predictive of malignant cytology. Among surgical cases, microcalcification (P <.001) and irregular margins (P =.04) were significantly predictive of malignant histology; 170 patients with initial benign cytology and 161 with indeterminate cytology underwent surgery. Microcalcification was significantly associated with malignancy among cases with indeterminate cytology (P =.04) but not among cases with benign cytology (P =.23); however, only 13 of 33 cases with benign cytology and microcalcifications underwent surgery. Conclusion Presence of microcalcification increases the risk of malignancy in thyroid nodules with indeterminate cytology and may thus aid in selection of cases for surgery.