1. Pheochromocytoma
Wendy Blount, DVM

2. Pheochromocytoma
Uncommon tumor of the chromaffin cells in the adrenal medulla
Occasionally can arise from chromaffin cells outside the adrenal gland
Right adrenal more common than left
Bilateral has been reported
Most are malignant and functional
Produce catecholamines
Epinephrine
Norephinephrine
Dopamine (rare)

3. Pheochromocytoma 40%have metastasized at the time of diagnosis
Regional lymph nodes (sublumbar)
Liver
Lung
Bone
CNS
Many invade the caudal vena cava
Sometimes when the tumor is not found on ultrasound

4. Clinical Signs 60% diagnosed on necropsy
Symptoms can be non-specific and episodic
Malignant hypertension (>95%) - HALLMARK
Sustained hypertension with severe episodes (50%)
Normotensive between episodes (25%)
Stable hypertension (25%)
Normotension does not rule out pheochromocytoma
Systolic BP can be >300mmHg
Tachyarrhythmia
Panting, nervousness
Exercise intolerance, weakness (62%), collapse (29%)

5. Clinical Signs Bleeding diathesis Abdominal mass (10%)
Hyphema, retinal detachment
Bleeding from the gums
CNS bleed
Abdominal mass (10%)
Palpable mass
Abdominal discomfort
Abdominal effusion, caudal peripheral edema
Can present as an acute retroperitoneal or abdominal bleed
Or ascites (pure or modified transudate) due to portal hypertension

6. Clinical Signs Tumor thrombus – Caudal vena cava Fever PU-PD (29%)
Ascites
Caudal peripheral edema
Fever
PU-PD (29%)
Anorexia, weight loss
Vomiting, diarrhea, constipation

7. Labwork CBC Serology Urinalysis Anemic if significant bleed
Increased white count – response to tumor
Serology
Liver enzymes usually elevated
Can mimic hyperadrenocorticism
Urinalysis
Poorly concentrated urine
with proteinuria

8. Cardiac Work-Up ECG Echocardiogram – hypertrophic cardiomyopathy
Sinus tachycardia early on
Catecholamine induced cardiomyopathy leads to life threatening arrhythmias
APCs, VPCs, idioventricular rhythms, 3rd degree AV block
Echocardiogram – hypertrophic cardiomyopathy
Chest x-rays
Look for metastasis (3 views) – 15%
nodules 3-5mm+
VetBLUE® ultrasound – nodules 1-3mm+

9. Abdominal Imaging
Abdominal mass may be seen on radiographs or on ultrasound
Cranial to the kidney(s)
Check caudal vena cava for invasion
80% sensitivity, 90% specificity
CT 92% sensitivity, % specificity
Adrenal(s) may be enlarged with mixed echogenic pattern effacement of normal architecture (60-80%)
Normal ultrasound does not rule out pheochromoctyoma

10. Abdominal Imaging
adrenal tumor invading cava
Abdominal mass may be seen on radiographs or on ultrasound
Cranial to the kidney(s)
Check caudal vena cava for invasion
Adrenal(s) may be enlarged with mixed echogenic pattern effacement of normal architecture (60-80%)
Normal ultrasound does not rule out pheochromoctyoma

11. Abdominal Imaging
adrenal tumor
Abdominal mass may be seen on radiographs or on ultrasound
Cranial to the kidney(s)
Check caudal vena cava for invasion
Adrenal(s) may be enlarged with mixed echogenic pattern effacement of normal architecture (60-80%)
Normal ultrasound does not rule out pheochromoctyoma

12. Cytology FNA of adrenal masses is not recommended
Any adrenal tumor has propensity to bleed
Catecholamine storm is possible with pheo
Cytology is not highly correlated with malignancy with neuroendocrine tumors
Cytology can identify the tumor as neuroendocrine
Naked uniform round nuclei
Cells in rosettes and rows
Fine chromatin & inconsistent nucleoli

13. Cytology FNA of adrenal masses is not recommended
Amy adrenal tumor has propensity to bleed
Catecholamine storm is possible with pheo
Cytology is not highly correlated with malignancy with neuroendocrine tumors
Cytology can identify the tumor as neuroendocrine
Naked uniform round nuclei
Cells in rosettes and rows
Fine chromatin & inconsistent nucleoli

14. Cytology FNA of adrenal masses is not recommended
Amy adrenal tumor has propensity to bleed
Catecholamine storm is possible with pheo
Cytology is not highly correlated with malignancy with neuroendocrine tumors
Cytology can identify the tumor as neuroendocrine
Naked uniform round nuclei
Cells in rosettes and rows
Fine chromatin & inconsistent nucleoli

15. Plasma Free Metanephrines
Can measure plasma free metanephrines or fractionated urine metanephrines
Much higher in people and dogs with pheochromoctyomas
Requires special handling of the sample – contact the lab
Add acid, refrigerate, protect from light
Phenoxybenzamine, corticosteroids and tricyclic antidepressants can falsely increase metanephrines

16. Treatment Adrenalectomy is treatment of choice
perioperative mortality 50%
Pre-treat with phenoxybenzamine for 20 days
Reduces perioperative mortality to 20%
Treat hypertension
If they survive surgery mean survival is 1 year

17. Acknowledgements
Shelly Olin, ACVIM, Alejandro Garcia, Linda Shell, ACVIM (Neurology). Veterinary Information Network (VIN) – Canine Associate.