Adrenal tumours
Key points
Phaechromocytoma and paragangliomas
Paediatric Phaechromocytoma 1:500,000, 30% extra adrenal, 3% malignant
Arise from paraganglial/neural crest cells
Paragangliomas may arise from either sympathetic or parasympathetic precursors - may or may not secrete catecholamines
Adrenaline metabolised to metanephrine + Vanillylmandelic acid (VMA)
Noradrenaline to normetanephrine + VMA
Dopamine to Homovanillic acid (HVA)
Paragangliomas = extra adrenal
In older nomenclature, functional paragangliomas that secrete catecholamines were classified as extra-adrenal Phaechromocytoma
Majority of head and neck paragangliomas - nonfunctional
Majority of intra-abdominal paragangliomas secrete catecholamines
Majority are benign, only way to distinguish malignant is metastases
10% will have metastases - lymph nodes, liver, lungs, bone
Dopamine, adrenaline + noradrenaline (most commonly) released
Adrenaline predominates in MEN2
Around 80% of cases have identifiable genetic mutations e.g. VHL (Von Hippel-Lindau), RET (MEN 2A/2B), and NF1 (Neurofibromatosis type 1)
Investigations:
Biopsy not indicated usually
24 hour fractionated urine catecholamines + homovanillic acid, metanephrines + normetanephrines
Vanilylmandelic acid is directly proportional to the size of the tumour
Sensitivity of 90%, Specificity of 98% for Phaeo + PGL
Plasma catecholamines - unreliable
Plasma metanephrines - sensitivity 97%, specificity 85%
Chromogranin A - serum biomarker
Imaging:
CT/MRI
I123 - metaiodobenyzlguanidine MIBG - Potassium iodide must be given before MIBG to block thyroid uptake
F18fluorodopamine, F18fluorodeoxyglucose PET scanning is becoming more common
Pre-operative considerations:
Metyrosine can block catecholamine production - expensive - use only in refractory cases
Mitotane treats medically - blocks adrenal steroid hydroxylation - not as good outcomes as surgery
Pre-op the hypertension must be treated with alpha blockers until postural hypotension occurs, and then adding beta blockers to treat reflex tachycardia until the blood pressure is normal. May need to give salt replacement and admit for IV fluids
Operation:
Always ligate vein first to avoid catecholamine systemic release
Approach as per kidney - mobilise colon, duodenum on right. Adrenal will be anterior to respective crus
Total adrenalectomy, and excision of all hot areas on MIBG
Retroperitoneal lymph node dissection
May include Organ of Zuckerkandl - ectopic adrenal medulla - a body of chromaffin cells near the origin of the superior mesenteric artery or aortic bifurcation
Can do cortical sparing surgery in patients with bilateral disease or with a syndrome - <5% 10 year recurrence rate and normal glucocorticoid function >50% of adults. Not recommended for patients with germ line SDHB mutations - risk of local recurrence and metastasis
Post op monitor for hypoglycaemia, hypertension and hypotension for 48 hours
For incidental tumours in children - should resect as higher incidence of neuroblastoma and malignant/hormonally active tumours
Monitor urine metanephrines etc for 6 weeks post op - any increase should raise the concern of relapse, metastasis, metachronous tumour
Adrenocortical tumours
p53 mutations are a risk factor for adrenocortical carcinoma (ACC)
ACC is also associated with Beckwith-Weidemann Syndrome (BWS), Li-Fraumeni syndrome, familial adenomatous polyposis (APC gene mutation) and Lynch syndrome, Carney complex, neurofibromatosis type 1 and MEN 1
Most cortical tumours are hormonally active in children
Can be virilising or feminising in boys or girls (feminising tumours are usually malignant)
Metastases - lymph nodes, liver, lungs, bone
Hyperaldosteronism: Metabolic alkalosis from loss of hydrogen ions in urine to retain K+
Investigations:
To distinguish aldosterone secreting tumour from bilateral adrenal hyperplasia (BAH) - dexamethasone suppression - will normalise aldosterone and renin in BAH - could also do selective adrenal vein sampling
Only if tumour not seen on imaging
Wieneke or Weiss criteria to distinguish benign from malignant cortical tumours
Imaging:
CT/MRI
Operation:
Adrenalectomy
Age <3.5y and symptoms <6m are favourable
1 year survival 70%, 3 year 64%
Primary pigmented nodular adrenocortical disease (PPNAD)
Bilateral hyperplasia
ACTH independent Cushing
Autosomal dominant
Skin tumours, pigmented lesions, cardiac myxomas, schwannomas and various endocrine tumours
Needs bilateral adrenalectomy - lifelong prednisolone + fludrocortisone
Oncocytoma
Rare epithelial cell tumour of adrenal gland
References
Kanthan R, Senger JL, Kanthan S. Three uncommon adrenal incidentalomas: a 13-year surgical pathology review. World J Surg Oncol. 2012 - 25% malignancy rate
Escobar, Mauricio (Tony) A, et al. "Adrenal Cortical Tumors." Pediatric Surgery NaT, American Pediatric Surgical Association, 2020. Pediatric Surgery Library, www.pedsurglibrary.com/apsa/view/Pediatric-Surgery-NaT/829516/all/Adrenal_Cortical_Tumors.
Escobar, Mauricio (Tony) A, et al. "Adrenal Medullary Tumors." Pediatric Surgery NaT, American Pediatric Surgical Association, 2020. Pediatric Surgery Library, www.pedsurglibrary.com/apsa/view/Pediatric-Surgery-NaT/829517/all/Adrenal_Medullary_Tumors.