Case Study

Right adrenal mass with caudal vena caval invasion in a 12 year old FS Portuguese Water Dog

A 12-year-old FS Portuguese Water Dog with hypothyroidism (on Soloxine) was presented for limping. Abnormalities on physical examination toe touching on the left hind leg and pain palpated along L3-L5. The patient was treated with Dexamethasone and Previcox. The patient was presented several days later for hip and stifle radiographs but shortly after being sedated became extremely cyanotic and bradycardic. The patient was intubated and given IV glycopyrolate. After stabilization, an EKG was performed, which revealed sinus tachycardia. A left ACL tear was seen on radiographs. Abnormalities on CBC and blood chemistry were mild leukocytosis, thrombocytosis, neutrophilia, mildly elevated AST activity, mild hypoglycemia, hyperkalemia, and elevated CPK. Post-pill T4 and resting cortisol level were both within normal limits, and an ACTH stimulation showed a normal response.

DX

Right adrenal mass with invasion into the caudal vena cava

Sonographic Differential Diagnosis

Right adrenal gland mass with slight phrenic invasion in the vena cava suggestive of a pheochromocytoma. Compensated mitral insufficiency. Elevated left ventricular outflow velocity. Systemic hypertension.

Image Interpretation

Given the hyperdynamic state of the heart on an echo, an abdominal sonogram was performed to rule out concurrent adrenal disease or other potential causes of hyperdynamic state. The left adrenal gland was normal in size and contour at 0.6 x 2.3 cm. However, there was a large mass on the right adrenal gland that measured 6 x 3.15 cm with slight invasion into the right phrenic vein. This had luminal entry into the vena cava to approximately 0.5 cm. This is still potentially resectable; however, the surgeon should be expected to potentially perform a minor venotomy of the vena cava at this point. Given that the patient is not PU/PD this is highly suggestive of pheochromocytoma. Blood pressure measurements were then taken and measured 235/119.

Outcome

Therapy with Norvasc at 2.5 mg SID and low dose aspirin was recommended. Monitoring of blood pressure measurements and surgical consultation were both advised. A follow-up echocardiogram with re-assessment of the adrenal mass within 3-months was recommended. If surgery was not an option in this patient, control of hypertension and potential thromboembolic episode would be the main theme of therapy. The patient went for a surgical consultation for the adrenal mass, as well as the left cruciate tear, and it was determined that the risk of death during surgery was too great. At last communication, the owners were keeping the patient comfortable, and using a sling to help the patient ambulate.

Clinical Differential Diagnosis

Acute collapse – heart (cardiomyopathy, myocarditis, cardiac tamponade), pulmonary embolism, drug reaction, anaphylaxis, insulinoma, pheochromocytoma, vagal stimulation (brain/thorax/abdominal pathology).