Pheochromocytoma

Snapshot

A 40-year-old gentleman presents with episodic headaches and palpitations. Attributing it to his tendency to worry excessively, he put it off for several months until he began to sweat episodically too. In the clinic, his blood pressure is found to be elevated at 160/120 mmHg. Plasma metanephrines are elevated and an abdominal CT scan reveals an adrenal mass.

Introduction

Nonmalignant tumor of adrenal medulla
- most common adrenal tumor in adults (vs neuroblastoma, most common in children)
- composed of chromaffin cells that are normally stimulated by acetylcholine
- secretes catecholamines causing episodic hypertension
Pathogenesis
- from chromaffin cells of neural crest origin
Epidemiology
- 40-50 years old
Rule of 10’s
- 10% malignant
- 10% bilateral
- 10% kids
- 10% extra-adrenal
  - bladder, organ of Zuckerkandl (bifurcation of aorta)
- 10% calcify
Associated conditions
- von Hippel-Lindau disease
- MEN 2A
- MEN 2B
neurofibromatosis type 1

Presentation

Symptoms are episodic
- 5 P’s
  - Pressure (↑ BP)
    Pain (headache)
  - Perspiration
  - Palpitations (tachycardia)
  - Pallor
- mediated by tumor secretion of epinephrine, norepinephrine, and dopamine
Physical exam
↑ BP (diastolic and systolic increase due to alpha adrenergic stimulation resulting in vasoconstriction)

Evaluation

Serology
- ↑ free metanephrine level
24-hour urine collection for diagnostic confirmation
- ↑ vanillyl mandelic acid (breakdown of norepinephrine and epinephrine)
- ↑ metanephrines (more sensitive than VMA)
Histology
chromaffin cells with enlarged dysmorphic nuclei

Differential Diagnosis

Treatment

In this sequence of events
- α-antagonist phenoxybenzamine to prevent unopposed α-action if β receptors are blocked
- β-blocker
tumor resection

Prognosis, Prevention, and Complications