Pheochromocytoma

Question 1

What is a paraganglioma?

Answer 1

Catecholamine secreting extra-adrenal tumor

Question 2

Where is a common site for a paraganglioma?

Answer 2

Organ of Zuckerkandl

- located at bifurcation of the abdominal aorta or origin of the IMA

Question 3

Signs/sx’s of pheochromocytoma?

Answer 3

Episodic HA’s, tachycardia, diaphoresis, palpitations, paroxysmal HTN, flushing, nausea, chest pain, cardiomyopathy

Question 4

If pheochromocytoma found and pt is in early pregnancy, what do you do?

Answer 4

Due to high risk of maternal and fetal mortality, rec’d to terminate pregnancy and treat the pheo

Question 5

If pheochromocytoma found in a pt who is in her late second or third trimester, what do you do?

Answer 5

Caesarian section with excision of the pheo at the same time

- must NOT allow vaginal delivery as this may cause sudden massive catecholamine release

Question 6

What factors are known to induce symptomatic attacks?

Answer 6

Tyramine rich foods (beer, cheese, wine)
Nicotine
Anesthesia (propofol)
Cocaine

Question 7

Histologically, what are two things to know for pheo’s

Answer 7

Zellballen pattern (small nests of cells with an alveolar pattern to them)
- very specific

• Chromogranin A staining (brown stain for neuroendocrine tumors
• highly sensitive

Question 8

Screening test for pheo’s

Answer 8

Plasma free fractionated metanephrines

- ~99% sensitive

Question 9

Confirmatory test for pheo’s

Answer 9

24-hr urine catecholamines

- ~99% specific

Question 10

What if the confirmatory test for pheo’s in inconclusive, what are the next two tests?
- describe them

Answer 10

1. Clonidine suppression test
   - give 0.3mg clonidine, then check metanephrines in 3 hours
   - if pheo +, then there will be NO SUPPRESSION
   - if essential HTN, then ~50% reduction in serum catecholamines
2. Glucagon stimulation test
   - give 2mg glucagon IV, then check metaneprines in 3 hours
   - if pheo +, then there are increased catecholamines

Question 11

What is the specific imaging study for pheo’s?

In what scenario(s) is it useful?

Answer 11

Iodine-131-labeled MetaIodoBenzylGuanidine (MIBG)
- radionuclide that highlights elevated levels of Norepi.

Useful in extra-adrenal tumors, metastatic w/u, or multiple pheo’s

Question 12

What is the MRI buzzword for pheo’s?

Answer 12

Light bulb sign on T2

• marked hyperintesity on T2 imaging
• however, this isn’t sensitive or specific, since pheo’s or more heterogenous in nature

Question 13

Preoperative treatment of pheo’s before adrenalectomy:

Answer 13

1st, give non-competitive alpha blocker (phenoxybenzamine) for 2 weeks

2nd, add additional beta blockade (propranolol)

**3rd, aggressive intravenous hydration

Question 14

If pheo is determined to be malignant (excised, unresectable, or continued symptomatic), what treatments are offered?

Answer 14

Chemotherapy: Cyclophosphamide, vincristine, dacarbazine

**Metyrosine

Question 15

What is the MOA of metyrosine, used for refractory pheo’s?

Answer 15

Tyrosine hydroxylase inhibitor, thus decreasing catecholmine synthesis

Question 16

During a pheochromocytoma excision, what do you ligate first?

Answer 16

Adrenal veins!

• likely to see immediate decrease in BP
• “dissect the body from the adrenal gland” meaning do NOT manipulate the adrenal gland until vascular control

Question 17

What are the rule of 10’s regarding pheo’s (six of them)

Answer 17

1. 10% pediatric (increased bilaterality in kids)
2. 10% bilateral
3. 10% malignant (defined by metastasis, NOT local invasion)
4. 10% normotensive
5. 10% extra-adrenal (therefore increased risk malignancy)
6. 10% familial (increased risk B/L and malignant)

Question 18

Name some of the syndrome that have increased risk of pheochromocytoma (5 of them)

Answer 18

1. von Hippel-Lindau
2. von Recklinghousens’s disease (NF 1)
3. MEN 2 Syndrome (“PTC syndrome”)
4. Tuberous sclerosis
5. Sturge-Weber Syndrome

Question 19

Mutation in von Hippel Lindau

Answer 19

3p25

*VHL = 3 letters = 3p

Question 20

Mutation in MED 2 syndromes

Answer 20

RET oncogene on 10q11

Question 21

Presenting features of MEN2A syndome (Sipple Syndrome)

Answer 21

Pheo, medullary thyroid carcinoma, parathyroid hyperplasia

*think of a square

Question 22

Presenting features of MEN2B syndrome

Answer 22

pheo, medullary thyroid carcinoma, mucosal/GI neuroma, marfanoid features

*think of a diamond shape

Question 23

Feature of Stuge-Weber syndrome

Answer 23

port wine stain, seizures, mental retardation, AVMs

Question 24

Features of Tuberous sclerosis

Answer 24

adenoma sebaceum, seizures, mental retardation, AML