Chap 311 : Pheochromocytoma

Question 1

Catecholamine biosynthesis

Answer 1

Tyrosine → DOPA → Dopamine → NE → Epinephrine

NE → Epinephrine : PNMT
Catecholamine → Normetanephrine : COMT

Question 2

PNMT expression ?

Answer 2

Limited to adrenal medulla
Need for high cortisol level

Question 3

Mutation

Answer 3

Succinate Deshydrogenase Subunit D ( SDHD)

Question 4

Primary source of MN?

Answer 4

Metabolism of catecholamine in
- adrenal medulla (majority)
- GI, liver

Autonomous and continuous process

Question 5

Metastasis localization ?

Answer 5

Liver, kidney, spleen, LN, lungs, heart, CNS, bone or vertebral canal

Question 6

Clinical pathology

Answer 6

Liver enzyme (10-25%) : systemic hypertension
Hypo isosthenuria
Hyperglycemia (20%)
Proteinuria (20%) : hypertensive glomerulopathy

Question 7

Invasion of caudal vena cava

Answer 7

15 - 55%
(More frequent with right sided)

Question 8

Inhibin ?

Answer 8

Undetectable with pheo but not with HAC
Only in neutered dogs

Question 9

Phenoxybenzamine

Answer 9

Alpha receptor antagonist
Start at 0.25 mg/kg BID, increase to 1 mg/kg
Adverse effect : hypotension, GI