Pheochromocytoma is one of those “buzzword” endocrine tumors where the presentation is basically the diagnosis—you just need a fast way to recall the classic triad + the key testing and management steps on exam day.
The Acronym Trick: PHEO
Use PHEO to remember the high-yield core:
- P — Pressure (paroxysmal hypertension)
- H — Headache
- E — Episodic sweating (diaphoresis)
- O — (palpitati)Ons / tachycardia
One-liner (the shareable version)
Pheochromocytoma = catecholamine-secreting adrenal medulla tumor causing episodic headache, sweating, and palpitations with paroxysmal hypertension.
A Quick Visual Mnemonic (mental image)
Picture a PHEO wearing a “fight-or-flight” Epi-pen strapped to its chest:
- Every time it clicks, you get a burst of catecholamines → BP spikes, pounding headache, drenched shirt, racing heart.
What It Is (USMLE framing)
- Tumor type: Chromaffin cell tumor (usually adrenal medulla) secreting catecholamines (NE > Epi)
- Syndromes: Can be sporadic or associated with MEN 2A/MEN 2B, NF1, VHL
- Rule of thumb: Think episodic symptoms + hypertension that comes in spells
High-Yield Presentation Clues
Classic symptoms
- Headache
- Diaphoresis
- Palpitations/tachycardia
- Paroxysmal hypertension (can be sustained too)
Extra exam-friendly hints
- Pallor, tremor, anxiety/panic-like episodes
- Weight loss
- Hyperglycemia (catecholamines ↑ glycogenolysis/gluconeogenesis)
- Spells triggered by: surgery/anesthesia, stress, exercise, sometimes tyramine-containing foods or certain meds
Diagnosis: What to Order (and why)
Best initial tests (Step-style)
Order metanephrines because they’re more stable metabolites than catecholamines.
| Test | When/Why it’s used | High-yield note |
|---|---|---|
| Plasma free metanephrines | High sensitivity; great when suspicion is high | Often the preferred screening test |
| 24-hour urine fractionated metanephrines | Good confirmatory option; captures episodic secretion | Helpful when symptoms are intermittent |
Then localize
- CT/MRI abdomen to find the adrenal mass
- If extra-adrenal suspected: functional imaging (institution-dependent)
Management: The “Don’t Kill the Patient” Order of Operations
The golden rule
Block alpha before beta.
If you give a beta-blocker first, you leave unopposed alpha-1 vasoconstriction → hypertensive crisis.
Stepwise treatment (classic board answer)
- Alpha-blockade first
- e.g., phenoxybenzamine (irreversible) or selective blockers (e.g., doxazosin)
- Then add beta-blocker (only after adequate alpha blockade)
- for tachycardia
- Surgical resection (definitive)
Pathology & Associations You Should Recognize Fast
- Location: adrenal medulla (or extra-adrenal paraganglioma)
- Histology buzzword: Zellballen (“cell balls”) nests of chromaffin cells
- Genetic associations to name-drop on questions:
- MEN 2 (RET mutation): medullary thyroid carcinoma + pheo ± hyperparathyroidism (2A)
- VHL
- NF1
Rapid-Fire USMLE Pearls (Quick Recall)
- Episodic symptoms + HTN → think pheo
- Screen with metanephrines, not random catecholamines
- Alpha then beta (phenoxybenzamine → propranolol/metoprolol)
- Consider familial syndromes, especially with bilateral tumors or young patients