Carcinoid syndrome vs Pheochromocytoma
How to tell Carcinoid syndrome and Pheochromocytoma apart when a board question makes them look alike.
Carcinoid is serotonin flushing/diarrhea/wheezing with 5-HIAA; pheochromocytoma is catecholamine headache/sweating/palpitations with metanephrines.
Side by side
Flushing, secretory diarrhea, wheezing, pellagra-like dermatitis, right-sided valve lesions, and elevated urinary 5-HIAA from serotonin excess.
Episodic headache, sweating, palpitations, tremor, severe hypertension, and elevated plasma or urinary metanephrines from catecholamine excess.
Neuroendocrine tumor serotonin reaches systemic circulation, often after hepatic metastases, causing vascular, GI, bronchial, and valvular effects.
Adrenal medulla or paraganglial chromaffin tumor releases catecholamines, driving alpha and beta adrenergic symptoms.
Elevated urinary 5-HIAA and right-sided tricuspid/pulmonic lesions support carcinoid syndrome.
Elevated plasma free metanephrines or urinary fractionated metanephrines support pheochromocytoma.
The trap
Both are episodic neuroendocrine syndromes with flushing or adrenergic symptoms, but GI-wheezing versus hypertensive catecholamine spells separates them.
The repair move
For episodic neuroendocrine symptoms, decide serotonin GI/valve syndrome versus catecholamine hypertension syndrome.
Try a free question
CoreA patient has episodic flushing, watery diarrhea, bronchospasm, right-sided valvular fibrosis, and elevated urinary 5-HIAA. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Carcinoid syndrome. Flushing, diarrhea, bronchospasm, right-sided valve lesions, and 5-HIAA point to carcinoid syndrome.
Why the other choices are tempting
- B. Pheochromocytoma causes catecholamine hypertension spells with elevated metanephrines.
- C. Thyroid storm causes severe thyrotoxicosis with abnormal thyroid labs.
- D. VIPoma causes watery diarrhea (WDHA syndrome) with hypokalemia and achlorhydria, but not serotonin-driven valve fibrosis or 5-HIAA elevation.
- E. Panic disorder does not cause 5-HIAA elevation or valvular fibrosis.
Flashcards
Tap a card to flip it.
What marker points to carcinoid syndrome?
Elevated urinary 5-HIAA points to serotonin-producing carcinoid syndrome.
What marker points to pheochromocytoma?
Elevated plasma or urine metanephrines point to pheochromocytoma.
Quick answers
What is the fastest way to tell Carcinoid syndrome from Pheochromocytoma?
Carcinoid is serotonin flushing/diarrhea/wheezing with 5-HIAA; pheochromocytoma is catecholamine headache/sweating/palpitations with metanephrines.
What is the key clue for Carcinoid syndrome?
Flushing, secretory diarrhea, wheezing, pellagra-like dermatitis, right-sided valve lesions, and elevated urinary 5-HIAA from serotonin excess.
What is the key clue for Pheochromocytoma?
Episodic headache, sweating, palpitations, tremor, severe hypertension, and elevated plasma or urinary metanephrines from catecholamine excess.
What is the common trap with Carcinoid syndrome vs Pheochromocytoma?
Both are episodic neuroendocrine syndromes with flushing or adrenergic symptoms, but GI-wheezing versus hypertensive catecholamine spells separates them.