CT evaluation of anaplastic thyroid carcinoma.

CT findings in 19 patients with anaplastic thyroid carcinoma were compared retrospectively with pathologic findings and the results of palpation. The carcinoma appeared as a large mass of low attenuation accompanied by dense calcification in 58% of the patients; there was necrosis in 74%. Often, adjacent structures were infiltrated. CT correctly showed tumor invasion of the carotid artery (7/7), internal jugular vein (9/10), larynx (5/6), trachea (8/10), esophagus (4/5), mediastinum (5/5), and regional lymph nodes (14/16). Seven patients (50%) had necrotic nodes. CT was superior to palpation in the detection of a primary tumor in one patient and of metastatic nodes in seven patients. It suggested a suitable place for biopsy in two patients, leading to a correct diagnosis. CT altered surgical planning in five patients with intrathoracic extension of the thyroid tumor, and in three patients with laryngeal or esophageal invasion of the tumor. CT can increase diagnostic accuracy in patients with anaplastic thyroid carcinoma by suggesting a likely diagnosis and by indicating an appropriate site for biopsy. It is indispensable in the planning of surgery for patients with this disorder.