Pheochromocytoma

Question 1

Pheochromocytoma arise from ____ cells

Answer 1

Catecholamine producing chromaffin cells

Question 2

How do we define malignant pheos in dogs?

Answer 2

If they locally invade or with distant metastasis

Question 3

What is the most commonly quoted number of malignant pheochromocytomas in dogs?

Answer 3

50%

30% locally invade and 20% present with distant mets - but these are based on old numbers

Question 4

where does pheos metastasise too?

Answer 4

LN, liver, spleen, kidneys, pancreas, lung, heart, bone and CNS

Question 5

T/F - Approximately 50% of dogs with pheos have another neoplasm

Answer 5

T

Question 6

What is the effect of cathecolamines?

Answer 6

The effect of epinephrine is concentration dependend: low - stimulate B2 receptors and lead to vasodilatation.

Higher concentration has effect on alpha 1 - cause constriction

• increase HR, increase RR, increase BP, decreased GI motility, Increase BG and increased alertness.

Question 7

What are the sex, age and breed predilections for pheochromocytoma+

Answer 7

there are none

Question 8

What are the clinical signs of pheochromocytoma?

Answer 8

Symptoms are based on the underlying cause:
- Excess cathecolamines
Anorexia, weightloss, lethargy, tachypnoea, dyspnoea, panting, tachycardia, arrytmia, collapse, pale mucus membranes, hemorrhage and acute blindness

• weakness, anxiety, pacing, disorientation, muscle tremors, seizure, pu/pd, vomiting, abdominal pain
• Invasive or ruptured tumor
  Amdominal enlargement, ascites, abdominal pain, hind limb edema.
• Mets

Question 9

What are the most frequent clinical signs of a pheochromocytoma?

Answer 9

Weakness, lethargy, tachypnoea, panting and collaps

Question 10

Which cardiac arrythmias are most common with a pheochromocytoma?

Answer 10

Tachyarrytmias; supraventricular or VPCS

Question 11

What are the most common hematological abnormalities with pheochromocytoma?

Answer 11

1. Anemia
2. stress leukogram
3. thrombocytopenia (8%)
4. thrombocytosis (6%)

Question 12

How many pheochromocytomas are mineralized?

Answer 12

10%

Question 13

Which cardiac abnormalities can be seen with pheochromocytoma?

Answer 13

1. Generalized cardiomegaly
2. Left or rightsided ventricular enlargement
3. Pulmonary edema

Question 14

Tumor thrombus in the caudal vena cava is documented in up to ______% of cases?

Answer 14

50-60% - and is more common on the right side vs. left.

Question 15

Is CT indicated as a part of the work-up for a pheo?

Answer 15

Yes- must assess vascular and muscle invasion appropriately

Question 16

What is the main ddx for pheo?

Answer 16

HyperA