Calcifications in thyroid nodules identified on preoperative computed tomography: patterns and clinical significance.

BACKGROUND: The purpose of this study was to evaluate the patterns and clinical importance of calcifications in thyroid nodules identified on preoperative computed tomography (CT).

METHODS: CT of 383 patients undergoing thyroid operations were reevaluated to identify thyroid calcification. A novel classification for thyroid calcifications on CT images was applied. The prevalence and patterns of calcification were classified, analyzed, and correlated with clinical and histopathologic findings.

RESULTS: Of the 383 patients, 135 (35.2%) had intrathyroidal calcifications identified on CT. Among these 135 patients, 65 (48%) were found to have thyroid cancer on definitive histopathology. The incidence of cancer was greater in calcified nodules (48%) than in noncalcified nodules (20%; P < .001). According to the calcification patterns, 2 of 9 (22%) nodules with peripheral calcification, 11 of 52 (21%) nodules with coarse calcification, 18 of 31 (58%) nodules with a single punctate calcification, and 34 of 43 (79%) nodules with multiple punctate calcifications were malignant. In the subset of 42 patients who presented with a solitary calcified nodule, 35 (83%) were found to have cancer. In addition, the incidence of lymph node metastases is greater in malignant nodules with calcification than in those without (48% vs 25%; P = .01).

CONCLUSION: Thyroid calcification found on preoperative CT may represent an increased risk for thyroid malignancy. When the pattern shows multiple punctate calcification or the calcification is noted within a solitary nodule, the risk of malignancy is high in this study.