Case Study

Left adrenal mass, suspected functional adenocarcinoma, in a 12 year old FS Labrador Retriever

A 12-year-old FS Labrador Retriever, currently being treated with Rimadyl and Tramadol for chronic swollen hocks, was presented for PU/PD and urine leaking urine that had not responded to Proin (phenylpropanalamine). CBC was within normal limits. Abnormalities on blood chemistry were elevated ALT and ALP activity. Adrenal function testing showed elevated urine cortisol: creatinine ratio, minimal suppression with the LDDST, and an exaggerated response on ACTH stimulation.

DX

Left adrenal mass, suspected functional adenocardinoma

Sonographic Differential Diagnosis

Solitary noninvasive left adrenal mass. Differentials include pheochromocytoma or adenocarcinoma (functional or nonfunctional); a benign tumor such as myelolipoma is considered less likely. The mass appears resectable but would need computed tomography to confirm lack of vascular invasion given its intimacy with the vena cava.

Image Interpretation

The left adrenal gland comprised a 4.5 x 4.1 cm mass with impingement upon the vena cava without evident invasion. The right adrenal gland was small in size and contour. It was isoechoic to the surrounding tissue at 1.8 x 0.85 cm. The vena cava was interrogated from the right and left side with no deficit in color flow signal.

Comments

The owners decided to treat medically and declined surgery owing to financial issues. The patient was lost to follow up.

Clinical Differential Diagnosis

Urine leaking – incontinence, PU/PD. Cushing’s disease – pituitary dependent, adrenal neoplasia.

Sampling

ACTH stimulation test done a month later showed a normal range after mitotane (Lysodren) treatment. Functional adenocarcinoma is likely. The patient was managed medically without surgery.