Pheochromocytoma

Vignette says 30 years old male with a history of uncontrolled hypertension presents to the emergency department with chief complaints of  palpitations, headache and profuse sweating over the past few months; He has a history of hypertension for which he takes amlodipine and losartan since 18 months; He doesn’t smoke but drinks alcohol occasionally; Vital signs show blood pressure of 160/100 mm of Hg, pulse rate of  140 bpm, respiratory rate of 18 breaths/min, oxygen saturation of 96% in RA and temperature of 98.7 F; Laboratory studies show increased 24 hours urinary catecholamines and its metabolites metanephrines (i.e. vanillyl mandelic acid, homovanillic acid); ECG shows sinus tachycardia with no other abnormalities; CECT of the abdomen and pelvis shows a well-defined mass arising from the right adrenal gland; Diagnosis?

Diagnosis is pheochromocytoma.

Pheochromocytoma is a rare catecholamine secreting tumor, which are derived from chromaffin cells (arise from neural crest) situated within adrenal medulla or extra adrenal paraganglioma; Pheochromocytoma is associated with multiple endocrine neoplasia type 2a (MEN 2a), multiple endocrine neoplasia type 2b (MEN 2b), von Hippel Lindau syndrome (VHL), neurofibromatosis type I (NF 1), hereditary paraganglioma syndrome; Approximately 0. 1 to 1 % of total cases of hypertension is due to pheochromocytoma. 

Types:- 
1. Adrenal pheochromocytomas:- The MC site in adrenal medulla; NE: E ratio is high as 20:1 
2. Extra adrenal pheochromocytomas (Paragangliomas):- The common sites are along the paraaortic sympathetic chain, within organs of zuckerkandl, along the sympathetic chain in the neck and mediastinum, in the wall of the urinary bladder; The extra adrenal pheochromocytomas secrete NE exclusively.

Pheochromocytoma is clinical manifested with signs and symptoms like paroxysmal hypertension, headache, diaphoresis, palpitations, pallor, dyspnea and anxiety attacks from excessive catecholamines (i.e. mainly norepinephrine and epinephrine) secreted either intermittently or continuously by chromaffin cells of the tumor; The paroxysmal attacks are generally precipitated by exertion, trauma, stress, induction of anesthesia, drugs (metoclopramide, steroids, TCA’s), contrast dye.
Presents with the triad of headache, diaphoresis, and palpitations with sustained or paroxysmal hypertension. 

Diagnosis:- 
1. Increased catecholamines and its metabolites metanephrines (e.g. vanillyl mandelic acid, homovanillic acid) in urine and plasma; 24 hour urinary catecholamines and urinary metanephrines is used for the screening of pheochromocytoma. 
2. Increased plasma fractionated metanephrines level is the gold standard method for the diagnosis of pheochromocytoma.
3. CT scan / MRI shows a well-defined mass arising from the adrenal gland.
4. Somatostatin receptor scintigraphy, to rule out paragangliomas.

Management:- 
1.Medical therapy includes selective alpha-1 blockers (prazosin, terazosin) or nonselective alpha blockers (phenoxybenzamine) and non-selective beta blockers (Propranolol) or selective beta blockers (Atenolol, Metoprolol); Beta blockers should be given only after the complete alpha blockade to prevent hypertensive crisis.
2. Surgical resection of tumor is the mainstay of treatment.