Prevalence of Thyroid Cancer in Thyroid Nodules with Dense Calcification

Background/Aims: High-resolution ultrasonography has made it possible to predict thyroid cancerswithout invasive procedures. Densely calcified nodules are difficult to image on ultrasound, and considering them to be high risk features for thyroid cancershas been controversial. The aim of this study was to evaluate the prevalence of malignancy in patients with densely calcified nodules using an analysis of clinical parameters related to the development of thyroid cancer. Methods: We retrospectively reviewed the thyroid sonographic findings and clinical characteristics of patients with thyroid noduleswho attended Chonnam National University Hwasun Hospital during a 5-year period (2,387 cases). Dense calcificationsincluded coarse dense calcificationand peripheral calcification(163 cases). Nodules with microcalcification(< 2 mm) were excluded from this analysis (154 cases). Ultrasonography-guided fine needle aspiration (FNA) was performed for all nodules with dense calcification. Results: Among the densely calcified nodules, 37 (22.7%) were malignant. The prevalence of malignancy in patients with densely calcified thyroid noduleswas higher than that in patients without calcification(p < 0.01). The incidence of malignancy was greater in coarse calcified thyroid nodulesthan in nodules with peripheral (egg-shell) calcification, but this difference was not statistically significant (30.1% vs. 16.2%, p = 0.101). Conclusions: Nodules with dense calcificationcarry a higher risk for malignancy than non-calcified nodules. Further, it is more difficult to obtain an adequate or diagnostic sample for nodules with dense calcification. Therefore, careful evaluation is necessary to diagnose malignancy in densely calcified nodules. (Korean J Med 2012;83:322-327)