Thyroid incidentalomas are incidentally found nodules by investigation methods; usually diagnosed by ultrasound (US), which are not evident by palpation. Besides their high prevalence, the possibility of the detection of "occult" carcinoma makes the thyroid incidentalomas an important finding. The aim of the present study was to describe the ultrasonografic features of thyroid incidentalomas according to the cytological diagnosis obtained by US-guided fine-needle aspiration cytology (FNA). A cross-sectional study was conducted from January/1996 to May/1998. Ninety-five patients of a radiologic clinic with a previous finding of incidentaloma were selected and their thyroid nodules were studied (US features and cytological analysis), being considered the cytologic study as gold standard. Nodules > 1.5cm were excluded. In the study period, 110 nodules were examined (95 patients, some of that with multiple nodules), being 74% were benign, 10% malign and 16% of the nodules with cytological diagnoses of uncertain lesion (excluded of the statistical analysis). Malign nodules presented the following US features: solid content (100%), irregular margins (54%) and microcalcifications (54%), with statistically significant differences of the benign ones. In 72% of the malign nodules, there were at least 3 of the 5 indicative features of malignancy: hipoechogenicity, solid content, absent halo, irregular margin and microcalcifications. Most of the studied incidentalomas was benign. Our findings suggest that certain features found in the US of incidentalomas as solid content, irregular margins and microcalcifications, are important due to their association with malignancy, mainly if they were found associated.
Thyroid incidentalomas; Thyroid nodules; Ultrasonography; Cytology; Malignancy