Pheochromocytoma Flashcards
What is a paraganglioma?
Catecholamine secreting extra-adrenal tumor
Where is a common site for a paraganglioma?
Organ of Zuckerkandl
- located at bifurcation of the abdominal aorta or origin of the IMA
Signs/sx’s of pheochromocytoma?
Episodic HA’s, tachycardia, diaphoresis, palpitations, paroxysmal HTN, flushing, nausea, chest pain, cardiomyopathy
If pheochromocytoma found and pt is in early pregnancy, what do you do?
Due to high risk of maternal and fetal mortality, rec’d to terminate pregnancy and treat the pheo
If pheochromocytoma found in a pt who is in her late second or third trimester, what do you do?
Caesarian section with excision of the pheo at the same time
- must NOT allow vaginal delivery as this may cause sudden massive catecholamine release
What factors are known to induce symptomatic attacks?
Tyramine rich foods (beer, cheese, wine)
Nicotine
Anesthesia (propofol)
Cocaine
Histologically, what are two things to know for pheo’s
Zellballen pattern (small nests of cells with an alveolar pattern to them) - very specific
- Chromogranin A staining (brown stain for neuroendocrine tumors
- highly sensitive
Screening test for pheo’s
Plasma free fractionated metanephrines
- ~99% sensitive
Confirmatory test for pheo’s
24-hr urine catecholamines
- ~99% specific
What if the confirmatory test for pheo’s in inconclusive, what are the next two tests?
- describe them
- 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 - Glucagon stimulation test
- give 2mg glucagon IV, then check metaneprines in 3 hours
- if pheo +, then there are increased catecholamines
What is the specific imaging study for pheo’s?
In what scenario(s) is it useful?
Iodine-131-labeled MetaIodoBenzylGuanidine (MIBG)
- radionuclide that highlights elevated levels of Norepi.
Useful in extra-adrenal tumors, metastatic w/u, or multiple pheo’s
What is the MRI buzzword for pheo’s?
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
Preoperative treatment of pheo’s before adrenalectomy:
1st, give non-competitive alpha blocker (phenoxybenzamine) for 2 weeks
2nd, add additional beta blockade (propranolol)
**3rd, aggressive intravenous hydration
If pheo is determined to be malignant (excised, unresectable, or continued symptomatic), what treatments are offered?
Chemotherapy: Cyclophosphamide, vincristine, dacarbazine
**Metyrosine
What is the MOA of metyrosine, used for refractory pheo’s?
Tyrosine hydroxylase inhibitor, thus decreasing catecholmine synthesis
During a pheochromocytoma excision, what do you ligate first?
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
What are the rule of 10’s regarding pheo’s (six of them)
- 10% pediatric (increased bilaterality in kids)
- 10% bilateral
- 10% malignant (defined by metastasis, NOT local invasion)
- 10% normotensive
- 10% extra-adrenal (therefore increased risk malignancy)
- 10% familial (increased risk B/L and malignant)
Name some of the syndrome that have increased risk of pheochromocytoma (5 of them)
- von Hippel-Lindau
- von Recklinghousens’s disease (NF 1)
- MEN 2 Syndrome (“PTC syndrome”)
- Tuberous sclerosis
- Sturge-Weber Syndrome
Mutation in von Hippel Lindau
3p25
*VHL = 3 letters = 3p
Mutation in MED 2 syndromes
RET oncogene on 10q11
Presenting features of MEN2A syndome (Sipple Syndrome)
Pheo, medullary thyroid carcinoma, parathyroid hyperplasia
*think of a square
Presenting features of MEN2B syndrome
pheo, medullary thyroid carcinoma, mucosal/GI neuroma, marfanoid features
*think of a diamond shape
Feature of Stuge-Weber syndrome
port wine stain, seizures, mental retardation, AVMs
Features of Tuberous sclerosis
adenoma sebaceum, seizures, mental retardation, AML
