17- pheochromocytoma

• Pheochromocytoma

  Rare neuroendocrine tumor of the sympathetic nervous system, arising from chromaffin cells in the adrenal medulla
• Pheochromocytoma

  • Secretes excessive catecholamines (epinephrine and norepinephrine)
  • Mostly sporadic, but may be part of familial disorder (MEN2A, MEN2B, Von Hippel Lindau, NF1àall autosomal dominant, children are 50% at risk)
  • Same incidence in men and women, peak age 40-50's
  • Pathology: Reddish brown, encapsulated, highly vascular, focal hemorrhage or calcification, cells arranged in whirls/sheets
• Rule of 10

  • 10% extraadrenal (in any portion of the paraganglionic system, esp. the organ of Zuckerkandl)
  • 10% bilateral
  • 10% familial
  • 10% in children
  • 10% with MEN
  • 10% malignant (invasion or distant metastasis)
• Presentation of pheochromocytoma

  • Classic triad: palpitations, headache (esp. occipital) & HTN (paroxysmal), sweating
  • Typically episodic/paroxysmal (come and go)
  • Others: weakness, fatigue, tremor, anxiety, weight loss, flushing, paresthesia, tachycardia, orthostatic hypotension
  • May have ­ WBCs, ­ RBCs, ­ glucose, lactic acidosis
• Complications of pheochromocytoma

  • Hyper or hypotensive crisis
  • MI, arrhythmia (­ HR), heart failure, stroke
  • Tumor hemorrhage
  • Renal failure, hypercalcemia, DIC
• Diagnosis of pheochromocytoma

  1. Screening tests: If low index of suspicion (pt presenting with symptoms only: resistant HTN or hyperadrenergic spells)àstart with 24-hour urinary fractionated catecholamines and metanephrines, If high index of suspicion (pt with family history, genetic syndrome, or incidentally discovered adrenal mass)àstart with plasma fractionated metanephrines

  2. Radiological evaluation: CT & MRI

  3. If negative: MIBG scintigraphy (shows extra-adrenal sources)
• Treatment of pheochromocytoma

  1. Definitive: surgical excision of tumor (laparoscopic)

  2. Preparation (VERY IMPORTANT to block effect of catecholamines): #1: alpha-adrenergic blocker (phenoxybenzamine or terazosin) for pre-op control of BP, #2: beta-adrenergic blocker (to control arrhythmia & ­ HR), IV fluids, MUST GIVE alpha-blocker BEFORE beta-blocker