Cystic papillary carcinoma of the thyroid gland: a new sonographic sign.

Cystic thyroid lesions are generally considered to be benign and managed by repeated aspiration and/or biopsy. We report characteristic sonographic signs in eight cases of cystic papillary carcinomas of the thyroid gland. In all eight cases, ultrasonography (US) revealed mostly cystic lesions with solid excrescences protruding into the cyst. These nodules contained multiple punctate echogenic foci suggesting calcification. In three of these cases the initial fine needle aspiration biopsy was negative. The 'calcified nodule in cyst' sign was found to be very specific for cystic thyroid carcinoma in a review of the ultrasound findings in 115 patients with nodular thyroid lesions. Careful evaluation and/or surgery should be recommended in patients who have such characteristic sonographic findings even if the fine needle aspiration result is negative.