Pathophysiology
1) tumor of the chromaffin cells of the adrenal medulla that secrete catecholamines (norepinephrine and epinephrine) and other substances 2) can also arise in extra-adrenal sites (paraganglioma) 3) metastasizes most commonly to regional lymph nodes, liver, bone, lung
Signs and Symptoms
1) most common presenting sign is hypertension 2) 50% experience paroxysmal hypertensive crisis, which worsens in frequency, duration, and severity 3) crisis is marked by severe headache, palpitations, tachycardia, sweating, anxiety, angina, and myocardial infarction 4) crisis can be precipitated by a mechanical increase in intra-abdominal pressure (deep palpation, heavy lifting) 5) other findings – fever, sinus bradycardia, orthostatic hypotension, heat intolerance
Characteristic Test Findings
Laboratory – 1) increased catecholamines in urine (vanillymandelic acid and metanephrine) 2) increased erythropoietin/hematocrit 3) increased sed rate 4) increased IL-6 5) increased amylase 6) hypoglycemia or hyperglycemia
Histology/Gross Pathology
1) highly vascular, encapsulated, reddish, spongy 2) presence of “zellballen” (nested malignant cells) 3) no histological differentiation between benign and malignant – considered malignant if the tumor has produced metastases
Associated Conditions
1) MEN-2 and MEN-3 2) von Hippel-Lindau 3) McCune-Albright 4) neurofibromatosis type 1 5) cholelithiasis
Biochemistry
1) release of catecholamines is not under neural control 2) also secrete endogenous opiods, erythropoietin, endothelin, and dopamine
Inheritance
1) more common in women 2) if solitary, more common on the right side 3) if part of MEN syndrome, usually bilaterl 4) very unusual after age 60 years 5) only 0.1% of all hypertensive patients
Treatment
1) definitive treatment is surgical removal 2) requires alpha-adrenergic blockade with phenoxybenzamine for 10-14 days preoperatively 3) beta-adrenergic blockade is added after alpha-blockade 4) treatment of hypertensive crisis – oral prazosin or phentolamine and nitroprusside for pressure control
Tips for USMLE
1) five Ps – palpitations, pallor, perspiration, pain (headache), pressure 2) 10% rule – 10% bilateral, 10% malignant, 10% extra-adrenal, 10% children, 10% calcify 3) areas of extra-adrenal involvement (paragangliomas) – retroperitoneum, urinary bladder, posterior mediastinum, carotid body, para-aortic (organ of Zuckerkandl), larynx
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