Unusual calcification in mixed papillary and follicular carcinoma of the thyroid gland.

An unusual egg-shell calcification was found in the thyroid gland on a routine radiograph. The 99mTc-pertechnetate thyroid image showed a cold nodule in the inferior pole of the left lobe which proved to be mixed papillary-follicular carcinoma. There was no characteristic pattern of calcification in the thyroid gland which would permit precise diagnosis of cancer; however, psammomatous calcification frequently occurs in papillary carcinoma of the thyroid.