Case Study

CT – Bilobar Adenomatous Hyperplasia of the Thyroid Gland in a 16 year old MN cat

The patient was diagnosed with hyperthyroidism about 2 years ago. Recently there has been a lack of treatment response. Palpable mass on left side of neck.

Note: Only a post contrast study has been sent. This was a second scan because the patient had some severe spasms during the first post contrast scan. The scan that was sent is about 4 minutes post contrast injection.

The patient was diagnosed with hyperthyroidism about 2 years ago. Recently there has been a lack of treatment response. Palpable mass on left side of neck.

DX

The computed tomographic findings match with bilobar adenomatous hyperplasia of the thyroid gland. A functional assessment cannot be made, but a reason for the lacking treatment response recently noted is not obvious. The potential for thyroid carcinoma is very low. Ectopic thyroid tissue is not seen from the basihyoid to the base of the heart in this computed tomographic scan so the overall potential for this has to be assessed as low.

Image Interpretation

Late post contrast series findings:
Both lobes of the thyroid gland show an irregularly undulating shape and parenchymal heterogeneity. There is asymmetrical enlargement of the thyroid gland mainly affecting the left lobe. In this late post contrast series multiple nodular changes of varying attenuation are seen within both lobes equally. There is a mass effect of the thyroidal lobes on the adjacent tissues. The left lobe displaces the common carotid artery and esophagus. Infiltrative growth is not evident. Multiple diffuse interstitial opacities are seen peripherally within the dependent portions of all lung lobes compatible with positional atelectasis. There are no changes indicative of pulmonary metastases noted within the visible aspects of the lung lobes. Mild accumulation of mucous within the trachea and esophagus caudal to the larynx is noted. The esophagus shows generalized dilation which likely is a function of the anesthetic drugs.