Diagnosis

Papillary thyroid carcinoma.

Findings

CT examination of the neck demonstrates a heterogeneously enhancing mass lesion that arises from the left lobe of the thyroid gland. This mass appears to invade and distort the esophagus towards the right, significantly compromising its lumen. This lesion is also seen to be abutting the posterior and left lateral borders of the trachea, causing minimal deformation. The mass continues inferiorly for some distance into the superior mediastinum.

Biopsy revealed papillary carcinoma of the thyroid.

Discussion

Papillary carcinoma of the thyroid accounts for 60% of all thyroid carcinomas with a peak incidence in the fifth decade. There is a female preponderance. Metastases are generally to regional lymph nodes, although hematogenous spread does occur to the lung in some instances. Survival is 90% at 10 years for those with occult / intrathyroidal cancer. Survival at 10 years decreases to 60% with extrathyroidal disease. Prognosis is worse for both groups given advanced age.

CT imaging of the thyroid gland is useful in that it cannot only provide additional information from other modalities, but it may even detect some lesions missed by either ultrasound or radionuclide imaging. Although there are no definite CT characteristics of a thyroid lesion to indicate malignancy, there are a few findings that may be suggestive. These include nodal disease in the neck and aggressive behavior such as bone or cartilage destruction. Interestingly, recurrent laryngeal nerve palsy is also a strong indicator of malignancy as benign thyroid disease rarely causes this problem.

1) Bergeron, Osborn and Som. Head and Neck Imaging. St Louis: The C.V. Mosby Company, 1984.

2) Dahnert. Radiology Review Manual. Baltimore: Williams & Wilkins, 1996.