Benign nodule designated as suspicious for malignancy as result of thyroid US in 52-year-old woman (false positive).Longitudinal US image of thyroid nodule in left mid-lobe shows hypoechogenicity, spiculated margin, and round shape (arrow); however, lesion was confirmed as spontaneously collapsed nodule of previous benign cystic thyroid nodule by consecutive US-fine needle aspirations and follow-up US.