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Pheochromocytoma

The document discusses the suprarenal medulla, focusing on pheochromocytomas and paragangliomas, their epidemiology, symptoms, and diagnostic methods. It outlines various hereditary conditions associated with these tumors, diagnostic tests for catecholamines, and the importance of medical and surgical management. Treatment involves alpha- and beta-blockade, with surgical resection being curative in many cases.

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Suprarenal Medulla Usama Ragab Youssif, MD Lecturer of Medicine Zagazig University Email: usamaragab@medicine.zu.edu.eg Slideshare: https://www.slideshare.net/dr4spring/ Mobile: 00201000035863
Suprarenal Gland
Medulla It is sympathetic ganglia which secretes CA.
Nomenclature
Pheochromocytoma and Ganglioma Phaeochromocytomas (aPCA) are chromaffin tumors arising from the adrenal medulla and secreting CA. 90% benign, 90% adrenal, 90% unilateral (bilateral in familial syndromes). Paragangliomas (PGL) are tumours arising from extra-adrenal sympathetic or parasympathetic nervous tissue.
Pheochromocytoma and Ganglioma (cont.) • Sympathetic paraganglia occur as follows: in prevertebral, paravertebral, thoracoabdominal, etc. They are termed extra-adrenal functional paraganglioma (eFPGL). • Parasympathetic paraganglia are located close to major arteries and nerves, e.g., carotid body, glomus jugulare, etc. They are termed head and neck paraganglioma (HNPGL), and only a minority of those shows endocrine activity (~25%).
Notes The cells in the adrenal medulla produce epinephrine and norepinephrine but the extra adrenal chromaffin cells make only norepinephrine. PCA is found in 0.1% of patients with severe hypertension and in less than 0.05% of all hypertensive patients. Familial PCA may be inherited as AD trait either alone or in combination with other abnormalities such as multiple endocrinal neoplasia type II.
Inherited syndromes of PCA MEN type IIa and IIb: AD, RET proto- oncogen, ch 10q. von Hipple Lindau: occulocerebellar angiomatosis: AD, VHL gene, ch 3p. von Reckling Hausen disease (NF type 1): AD, NFS 1 gene, ch 17q Succinate dehydrogenase (SDH) mutations: of 4 types A → D with eFPGL.
Epidemiology Equal sex incidence 3rd and 4th decade
Secretory products Adrenaline or noradrenaline and may be constant or episodic. Phenylethanolamine-N-methyltransferase (PNMT) is necessary for methylation of noradrenaline to adrenaline and is cortisol-dependent. Paragangliomas (exception—organ of Zuckerkandl) secrete noradrenaline only, as they lack PNMT. Small adrenal tumours tend to produce more adrenaline whereas larger adrenal tumours produce more noradrenaline, as a proportion of their blood supply is direct, rather than corticomedullary, and therefore, lower in cortisol concentrations. Pure dopamine secretion is rare and may be associated with hypotension. These tumours are more likely to be malignant.
Importance of diagnosis Fatal Crises Treatable Need Intervention Malignancy? Underlying genetic cause (>25% of cases)
Presentation The presence of palpitation, headaches, or sweating in a patient with hypertension should raise the diagnostic query of PCA. • General: Sweating and heat intolerance >80%. Pallor or flushing. Feeling of apprehension. Pyrexia
Presentation (cont.) Hypertension: Sustained or episodic hypertension often resistant to conventional therapy More commonly PCA are found incidentally following CT imaging, thus may not show any clinical signs and symptoms Neurological: headache (throbbing or constant) (65%), paraesthesiae, visual disturbance, seizures, tremors
Presentation (cont.) Cardiovascular and vasomotor: palpitations (65%), chest pain, dyspnea, postural hypotension, flushing. GI: abdominal pain, constipation?, nausea. Skin: livedo reticularis. Endocrine: paroxysmal thyroid swelling (noradrenaline-secreting). Others: weight loss, polyuria, nocturia
Why sometimes there is hypotension Dehydration Release of adrenomedulline
Complications 1. CVS: LVF, DCM (reversible), hypertension, arrhythmia 2. Pulmonary: pulmonary edema 3. Metabolic: impaired glucose tolerance, hypercalcemia 4. CNS: hypertensive encephalopathy, target organ damage
Factors that may precipitate crisis 1. Straining 2. Exercise 3. Abdominal palpation 4. Surgery 5. Drugs e.g., beta blockers, IV contrast, anesthesia, tricyclic antidepressant, metocloperamide, glucagon
Take Care Differential diagnosis • Anxiety-panic attacks • Hypoglycemia • Other causes of hypertension = 2ry hypertension • Diencephalic or autonomic epilepsy (attacks of hypertension with increased CA Endocrine causes of excess sweating • Thyrotoxicosis • Acromegaly • Hypoglycemia • Pheochromocytoma
Workup
Who should be screened? 1. Patients with a family history of MEN, VHL, NF1. 2. Patients with paroxysmal symptoms. 3. Young patients with hypertension. 4. Patient developing hypertensive crisis during general anaesthesia/surgery. 5. Patients with unexplained heart failure. 6. Patients with an adrenal incidentaloma.
Two Questions What is the lesion = screen Where is the lesion = localize
What is the lesion
1- 24h urine collection for catecholamines/metanephrines • The sensitivity of urinary VMAs is less than free catecholamines or metadrenalines and influenced by dietary intake and should not be used. • Urinary metanephrines are of similar sensitivity but of superior specificity to urinary catecholamines.
2- Plasma metanephrines • Plasma metanephrines are the most sensitive test for detection of catecholamine excess and have only slightly lower specificity than urinary metanephrines. • If plasma metanephrines are borderline, urinary metanephrines may be used for confirmation. • Plasma catecholamines are elevated by renal failure, caffeine, nicotine, exercise, and some drugs.
3- Clonidine Suppression test • It lowers the norepinephrine in normal persons but not in patients with PCA. • 300 mcg orally → failure of suppression to normal range within 120 and 180 minutes
Comparable tests Test Sensitivity % Specificity % Plasma metanephrines 97 92 Urinary metanephrines 85 95 Urinary catecholamines 88 78 Urinary VMA 65 88 Clonidine suppression test 97 MRI 98 70 CT 93 70 MIBG 80 95
List of medications and stimulants to avoid before the measurement of plasma and urinary catecholamines and metanephrines • Tricyclic antidepressants • Beta-blockers: labetalol* and sotalol • Acetaminophen • Phenoxybenzamine • Monoamine oxidase inhibitors • Antipsychotics • Sympathomimetics: ephedrine, pseudoephedrine, amphetamines, albuterol • Stimulants: caffeine, nicotine, theophylline • Miscellaneous: levodopa, carbidopa, alcohol, cocaine *Labetalol interferes only with certain assays
Where is the lesion
Localization It is easily localized (large) in contrast to Conn’s syndrome MRI: Bright hyperintense image on T2. CT: Less sensitive and specific—less good at distinguishing between different types of adrenal tumours.
Localization (cont.) Metaiodo-benzylguanidine (MIBG) produces specific uptake in sites of sympathetic activity: Specificity is nearly 100%, localization of extra- adrenal tumors, performed preoperatively. PET scan: [18F]fluorodeoxyglucose (FDG) and the norepinephrine analogue [11C]metahydroxyephedrine (mHED) have both been used as radionucleotides.
Algorithm for the tumor localization in patients with biochemically proven pheochromocytoma
CT and MRI
MIBG
What about genetic condition? When to screen? 1. Bilateral tumours. 2. Extra-adrenal tumour, including head and neck. 3. Age of onset (<50 years 45%). 4. Malignancy. MEN II VHL NF1 Serum calcium. Serum calcitonin (phaeochromocytomas precede medullary thyroid carcinoma in 10%). Ophthalmoscopy—retinal angiomas are usually the first manifestation. MRI—posterior fossa and spinal cord. US of kidneys—if not adequately imaged on MRI of adrenals. Clinical examination for café-au-lait spots and cutaneous neuromas.
Treatment
1- Medical α-blockade must be commenced before B-blockade to avoid precipitating a hypertensive crisis due to unopposed stimulation It is essential that any patient is fully prepared with α- and B- blockade before receiving IV contrast or undergoing a procedure, such as venous sampling or surgery. α-blockade—commence phenoxybenzamine as soon as diagnosis made. Start at 10mg 2× day by mouth, and increase up to 20mg 4× day (doxazosin is an accepted alternative).
1- Medical (cont.) B-blockade—use a B-blocker, such as propranolol 20–80mg 8-hourly by mouth, 48–72h after starting phenoxybenzamine and with evidence of adequate α-blockade (generally noted by a postural fall in BP). Labetalol is not recommended Treatment is commenced in hospital.
Metyrosine • Metyrosine (tyrosine hydroxylase inhibitor) blocks the formation of norepinephrine and epinephrine. • It may be used when patients are intolerant of the adrenergic blockers.
2- Surgical • Surgical resection is curative ≈ 75%. • Need expert anesthetic team: tumour handling → major changes in BP ± arrhythmias. • Surgery may be laparoscopic if the tumour is small and apparently benign.
Risk factors for haemodynamic instability during surgery include High noradrenaline concentration Large tumour size Postural drop after B-blockade, and a MAP >100mmHg
Follow-up Clinical & biochemical follow up after surgery. Cure is assessed by 24h urinary free catecholamine measurement after 2 weeks post-operatively. CA levels should be checked annually Chromogranin A is also a useful marker
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