Pheochromocytoma

Question 1

Pheochromocytoma is a tumor of

CS

most pheo. dx:

definitive tx:

preoperative, perioperative, and postoperative management may be challenging

w. sx. even dogs with vena caval thrombi may experience a significant survival time of:

Answer 1

chromaffin cells of the adrenal medulla

if functional - hypertension and manifestations of the
elevated blood pressure, weakness, syncope, lethargy, vomiting, diarrhea, tachypnea, abdominal distention, tachyarrhythmias, bradyarrhythmias, and abdominal pain

abdominal imaging or during PM

surgical excision

18 months to greater than 4 years

Question 2

MENS

Answer 2

multiple endocrine neoplasia syndrome

In humans this is a heritable constellation of two or more
endocrine neoplasias (or hyperplasia), usually involving the parathyroid and thyroid glands in addition to the adrenal glands

Question 3

most pheo dx.

Answer 3

PM 48-80%

Question 4

do tumors met?

Answer 4

may be both locally invasive and metastatic

pheochromocytomas in humans secrete NE

Question 5

what % have CS

Answer 5

30-50% (only 0.13% of all canine tumors)

Question 6

what is budd-chiari like syndrome

Answer 6

resulting from tumor invasion and extension up the

caudal vena cava = occlusion of hepatic vein that drains liver = effusion

Question 7

what % have causal vena cava involvment

Answer 7

15% to 38%

Question 8

dx:
CXR -
Abd US how many detected
draw back to US:

better yet:

Answer 8

mineralization sometimes
65% to 83%
can’t ddx. from other adrenocortical tumors
if small may miss

CT, MRI, scintigraphy

Question 9

MoA of diarrhea:

Answer 9

secrete hormone - vasoactive intestinal peptide

Question 10

must r/o:

why

Answer 10

HAC

adrenal mass may look same and similar CS sometimes

Question 11

urinary catecholamine:urine creatinine ratio:
increases could be ___ or ____
4x increase:

list 3 urine catecholamines:

___ was highly suggestive of pheochromocytoma:

false positives (5):

Answer 11

HAC or pheo
pheo

metanephrine, normetanephrine, vanillylmandelic acid

normetanephrine

excitement
exercise
vanilla-containing foods
phenoxybenzamine tx.
radiographic contrast agents

Question 12

clonidine suppression test

Answer 12

should decrease serum catecholamine levels in
normal patients but not in patients with a functional pheochromocytoma (because catecholamine release from the tumor is not neurally mediated)

Question 13

Provocation tests using( 4):

Moa:

recommended vs not recommended:

avoid as antiemetic/prokinetic:

Answer 13

metoclopramide, histamine, tyramine, and glucagon

increased secretion of catecholamines from the tumor, are not recommended because of the potential for inducing acute hypertensive crises

metoclopramide

Question 14

Preoperative Treatment
a-antagonist
minimum:

Answer 14

phenoxybenzamine (non-comp. a-antagonist)

1 week before anesthesia

Question 15

In humans, preoperative α-adrenergic

blockade decreased perioperative mortality from:

Answer 15

13-45% to 0-3%

Question 16

α-Methylparatyrosine

-ve

Answer 16

competitively inhibits tyrosine hydroxylase -
interfering with catecholamine biosynthesis

significant side effects and has not been studied in veterinary patients with pheochromocytoma

Question 17

GA
avoid:

safe GA protocol:

BP control:

Answer 17

1. anticholinergics
2. barbituates
3. acepromazine - long-lasting α-adrenergic antagonists may complicate intraoperative or postoperative treatment -especially if animal is pretreated w phenoxybenzamine

opioid
benzo
propofol
iso/sevo

nitroprusside for hypertension
esmolol SVT
lidocaine

Question 18

GA - blood type

If a venotomy is anticipated for removal of a thrombus:

removal of tumor can cause 1 of 2 things:
1.

Answer 18

if invading into caudal vena cava

external cooling may protect tissues during intraoperative interruption of blood flow and ischemia

Surgical manipulation = catecholamine release

Sx removal - CV collapse (no catecholamines)
= need NE and phenylephrine

Question 19

elective vs emergent mortality:

another study found:
-ve prognostic indicators:

thorough abdominal exploration why?:

% current neoplasia:

Answer 19

6% for elective
50% emergency

intraoperative mortality was 4.8%
BUN, nephrectomy = shorter survival times

metastatic disease
15% metastasis
39% had locally invasive tumors

54%

Question 20

post-op complications time frame:
%

complications:

Answer 20

24 to 72 hours postoperatively
30-51%

hypotension, bradycardia, ventricular arrhythmias, tachypnea, vomiting, and CPA, refractory hypertension after removal of

Question 21

does postop hypertension resolve?:

bilateral adrenalectomy -supplement:

explain postoperative hypotension:

do you tx this hypotension with NE?:

also monitor:

Answer 21

may or may not resolve, even with full excision

GC & MC

1. removal catech.
   vs. 2. decreased sensitivity to catecholamines

no - noncatecholamine pressors
vasopressin

BG - hypogly bc lack of stim

Question 22

medical management?:

chemo/radiation?:

Answer 22

phenoxybenzamine, b-blocker

unrewarding in humans

Question 23

Px:

with vena caval thrombi:

Answer 23

prognosis is guarded, hw. patients surviving post op. okay

even so may experience significant survival times, reported from 1.5 to 4 years