Case Study

Pheochromocytoma diagnosed by surgical excisional biopsy in an 8 year old FS mixed breed dog

An 8-year-old FS mixed breed dog was referred for partial anorexia and mild lethargy. Mild painful cranial abdomen was noted on physical exam. CBC and blood chemistry panel were unremarkable. Urinalysis revealed 3+ proteinuria with isosthenuria. Systolic blood pressure was 220 mm Hg.

DX

Pheochromocytoma

Sonographic Differential Diagnosis

Progressively enlarged and nodular right adrenal gland with pericapsular reactive fat but no current vascular invasion. Rule outs include pheochromocytoma, adenoma or functional adenocarcinoma.

Image Interpretation

Left adrenal gland was normal size and contour (Image 1). Preliminary evaluation found the right adrenal gland to be mildly heterogenous and slightly irregular in contour with minor increased capsular echogenicity (Image 2). The right adrenal gland measured 3 x 2 cm. Cortical-medullary distinction was lost. The adjacent vena cava in this image as well as in an oblique interrogation of the vena cava showed no invasion (Image 3). On ultrasound follow-up 2 weeks later the right adrenal gland has increased in length to 4.3 x 1.8cm. The right adrenal also now contained a focal hypoechoic nodule with capsular impingement, and the echogenic periocapsular ill-defined fat (suggestive for associated inflammation and capsular stretch) had become more extensive (Image 4). This presentation is suggestive for right adrenal adenoma or possible emerging adenocarcinoma or pheochromocytoma, which may be functional given the hypertension in the history. Given the differential growth noted between the orginal and follow-up sonograms, right adrenalectomy would be recommended.

Outcome

The patient was referred to a board certified surgeon for an exploratory laparotomy. Pre-operative blood work was performed and the serum biochemical profile showed hyperphosphatemia, hypercholesterolemia. The CBC showed a neutrophilia, lymphopenia and eosinopenia. A right adrenalectomy and biopsy were performed. Recovery from surgery was uneventful, and the histological diagnosis was a pheochromocytoma.

Hypertension and proteinuria resolved after surgical recovery. The patient did have recurrent chronic active pancreatitis that was medically managed over the following 5 1/2 years. The patient was imaged by sonogram every 2 months for 5 1/2 years by owner request to ensure that no further metastatic disease had occurred. Noelle presented this month for progressive CNS signs, rapid weight loss and stage 3 renal failure. The latest abdominal and cardiac sonograms 5 days prior to this post again revealed no evident new pathology other than chronic renal disease and stable pancreatic changes. Due to minimal response to therapy and suspected brain tumor after neurology consultation, Noelle was humanely euthanized Sept 5, 2013, five and a half years after her right adrenalectomy for pheochromocytoma.

Comments

I would like to personally commend Noelle’s owner for demonstrating a relentless dedication to her pet that is unprecedented in my career as a practitioner. I personally have never imaged any patient nearly as many times as I have Noelle – Eric Lindquist DMV, DABVP, Cert./Pres IVUSS.

Clinical Differential Diagnosis

Pancreatic pathology (pancreatitis, neoplasia), renal pathology (renolith, hydronephrosis, neoplasia, glomerulonephritis, early chronic kidney disease), intra-abdominal neoplasia (originating in the liver, spleen, stomach).