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

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

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.

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).

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.