June's Case of the Month

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Suspected Pheochromocytoma in a Canine

Kara Woody DVM

Patient Information:


Age: 9 years
Gender: Spayed Female            
Breed: Hound
Species:  Canine


History


Patient was found collapsed and shaking with pupils dilated.  She had been normal prior to this episode. 


Physical Exam Findings


Tachycardia, excessive panting, and trembling were found on physical exam.  She was normothermic. No neurological deficits were present. 


Laboratory Findings


Mild elevation in ALT and ALP
Chest and abdominal radiographs WNL
BP was 200mmHG with Doppler


Ultrasonographic Findings


The left adrenal has a heterogenous mixed echogenic irregularly shaped mass (16.2x23.3mm) present between the cranial and caudal poles.
The right adrenal gland was visualized and recognized as having normal shape, size (cdpole=5.0mm), position, and echogenicity for this breed. 
No adrenal invasion in the vena cava, phrenic vein thrombosis, or dystrophic mineralization were noted.


Abdominal Ultrasound Interpretation


Left Adrenal Mass-the findings are moderate-DDx: differentials include cortical & medullary neoplasia vs. benign hyperplasia

  • Cortical Neoplasia - Adrenal adenocarcinoma = Cushing's Dz (common)

  • Non-functional adenoma vs. myelolipoma vs. hyperplasia

  • Medullary Neoplasia - Pheochromocytoma

  • Functional adenoma


Discussion:


Pheochromocytoma is a catecholamine producing  tumor derived from the chromaffin cells of the adrenal medulla. Local invasion into the caudal vena cava is common and may affect resectability. The most common clinical signs are generalized weakness, episodic collapse, tachypnea, panting, tachycardia, cardiac arrhythmias, and possibly neurological signs secondary to systemic hypertension. 
On ultrasound, the contralateral adrenal gland is usually normal in size and shape. The diagnosis prior to surgery is primarily one of exclusion and it is important to rule out corticosteroid producing tumors.  
Surgery is the treatment of choice.  Advanced imaging may be recommended to evaluate for local invasion prior to surgery. Tachycardia, arrhythmias, and hypertension can occur during anesthesia so oral phenoxybenazamine is typically recommended 1-2 weeks prior to surgery.


Case Follow-up:


The patient was referred to a local surgical specialist where surgery was recommended for suspected pheochromocytoma.  The owners are currently considering.  

An irregularly shaped hypoechoic mass located between the cranial and caudal poles of the left adrenal gland.

An irregularly shaped hypoechoic mass located between the cranial and caudal poles of the left adrenal gland.

The normal appearing contralateral right adrenal gland.

The normal appearing contralateral right adrenal gland.

Special thanks to Metropolitan Emergency Animal Clinic for allowing us to collaborate on this case!