Adrenal gland

ADRENAL GLANDS 

Muayad Abass Fadhel Assistant professor Surgery department

Anatomy

Weight----- 4 g.inner adrenal medulla and the outer adrenal cortex .situated near the upper poles of the kidneys, in the retroperitoneum, within Gerota’s capsule.

Function of the adrenal glands 

Response to stress Catechol amines are secreted by the adrenal medulla corticosteroids, aldosterone and cortisol are synthesised in the adrenal cortex


Catechol amines act on α and β receptors on target organs:increase in blood pressure and heart rate; vasoconstriction of vessels in the splanchnic system and vasodilatation of vessels in the muscles; bronchodilatation; and increased glycogenolysis in liver and muscles: all necessary for the flight/fight

Zona glomerulosa produce aldosterone, which regulates sodium– potassium homeostasis. The target organs of aldosterone are the kidneys ,sweat and salivary glands and the intestinal mucosasodium retention and potassium excretionRegulatd by renin–angiotensin system and the serum potassium concentration.

zona fasciculata and zona reticularis synthesise cortisol and the adrenal androgens dehydroepiandrosterone (DHEA) and its sulphate (dehydroepiandrosterone sulphate (DHEAS)). precursors of androgens and are converted in peripheral tissues such as fat



Cortisol secretion is regulated by adrenocorticotrophic hormone (ACTH), which is produced by the anterior pituitary gland. The hypothalamus controls ACTH secretion by secreting corticotropin-releasing hormone (CRH). The serum cortisol level inhibits the release of CRH and ACTH via a closed-loop system (negative feedback loop).

Cortisol has numerous metabolic and immunological effects increases gluconeogenesis and lipolysis, decreases peripheral glucose utilisation, immunological response and muscular mass. It affects fat distribution, wound healing and bone mineralisa- tion; and alters mood (euphoria or, rarely, depression) and cortical alertness.

Incidentaloma

Definition Incidentaloma is an adrenal mass, detected incidentally by imag- ing studies conducted for other reasons, not known previously to have been present or causing symptoms.

Incidence

Autopsy….. 1.4 to 8.7 per centimaging studies in 1 per cent75 per cent are non-functioning adenomas but Cushing’s adenomas, phaeochromocytomas, metastases, adrenocortical carcinomas and Conn’s tumours can all be found

Diagnosis

Computed tomography (CT) or magnetic resonance imaging (MRI) should be performed in all patients with adrenal masses. adrenocortical car- cinoma increases with the size of the mass (25 per cent >4 cm). Adrenal metastases are likely in patients with a history of cancer elsewhere and the sole indications for biopsy of an adrenal mass is to confirm a suspected metastasis from a distant primary site.


Adrenal gland biopsy Never biopsy an adrenal mass until phaeochromocytoma has been biochemically excluded The indication for adrenal gland biopsy is to confirm adrenal gland metastasis

Treatment

non-functioning adrenal tumour greater than 4 cm in diam- eter and smaller tumours that increase in size over time should undergo surgical resection. Non-functioning tumours smaller than 4 cm should be followed-up after 6, 12 and 24 months by imaging (MRI) and hormonal evaluation.


Adrenal metastases
one-third of patients with malignant disease . most common primary tumours are breast, lung, renal, gastric, pancreatic, ovarian and colorectal cancer. In selected circumstances an adrenalectomy is appropriate, for example if it is the sole site of metastatic disease.

Adrenocortical carcinoma

Pathology : differentiation between benign and malignant adrenal tumours is challenging. tumors size, the presence of necrosis or haemorrhage and microscopic features such as capsular or vascular invasion. macroscopic features are commonly multinodularity and heterogeneous structure with haemorrhage and necrosis.

Clinical presentation

60 per cent of patients present with evidence of cortisol excess (Cushing’s syndrome)Patients with non-func- tioning tumours frequently complain of abdominal discomfort or back pain caused by large tumours.Adrenal tumours secreting more than one hormone in excess, or feminising/masculanising steroids are likely to be malignant.

Diagnosis 

measurements of DHEAS, cortisol and catecholamines to exclude a phaeochro- mocytoma and a dexamethasone suppression test MRI and CT are equally effective in imaging adrenocortical carcinoma MRI angiography is useful to exclude tumour thrombus in the vena cava CT scan of the lungs is recommended

staging

The World Health Organization classification of 2004 is based on the McFarlane classification and defines four stages: tumours <5 cm (stage I) or >5 cm (stage II), locally invasive tumours (III) or tumours with distant metastases(IV)


Functioning tumours tend to do worse than non-functioning, but have the advantage of a serum marker which can be used for follow up and disease monitoring.

Treatment

Complete tumour resection (R0) is associated with favourable survival and should be attempted whenever possible. In order to prevent tumour spillage and implantation metastases, the capsule must not be damaged. En bloc resection with removal of locally involved organs is often required and in case of tumour thrombus in the vena cava thrombectomy is needed. Laparoscopic adrena lectomy is associated with a high incidence of local recurrence and cannot be recommended


Tumors debulking plays a role in functioning tumours to control hormone excess Patients can be treated postoperatively with mitotane alone or in combination with etoposide, doxorubicin and cisplatin. Adjuvant radiotherapy may reduce the rate of local recurrence Restaging every three months is required as the risk of tumour relapse is high.

Prognosis

stage I or II disease -five-year survival rate of 25 per cent stage III and stage IV disease - five- year survival rates of 6 and 0 per cent, respectively.

Phaeochromocytoma and paraganglioma 

Definition Tumours of the adrenal medulla and sympathetic gan-glia which are derived from chromaffin cells and which produce catecholamines.

Aetiology

In total, 4 per cent of incidentalomas are phaeochromocytomasSporadic phaeochromocytomas occur around the fourth decade whereas patients with hereditary forms are diagnosed earlier.10 per cent tumour’ 10 per cent of tumours are inherited, 10 per cent are extra-adrenal, 10 per cent are malignant, 10 per cent are bilateral 10 per cent occur in children.

Hereditary phaeochromocytomas occur in several tumour syndromes: Multiple endocrine neoplasia type 2 (MEN 2): Familial paraganglioma (PG) syndrome:von Hippel–Lindau (VHL) syndrome: Neurofibromatosis (NF) type 1:

Pathology

greyish-pink on the cut surface and are usually highly vascularised. Areas of haemorrhage or necrosis are often observed


The differentiation between malignant and benign tumours is difficult, except if metastases are present. An increased PASS (phaeo- chromocytoma of the adrenal gland scale score), a high number of Ki-67-positive cells, vascular invasion or a breached capsule all lean more towards malignant rather than benign.

Phaeochromocytomas may also produce calcitonin, ACTH, vasoactive intestinal polypeptide (VIP) and parathyroid hor- mone-related protein (PTHrP).

Clinical features 

catecholamine excess and are typically intermittent. 90 per cent of patients with the combination of headache, palpitations and sweating have a phaeochromocytoma. Paroxysms may be precipitated by physical training, induction of general anaesthesia and numerous drugs and agents (contrast media, tricyclic anti- depressive drugs, metoclopramide and opiates). Hypertension may occur continuously, be intermittent or absent . A subset of patients are asymptomatic.

Diagnosis

determination of adrenaline and noradrenaline breakdown products, metanephrine and normetanephrine level, in a 12- or 24-hour urine collection.Determination of plasma-free metanephrine and normetanephrine levels also has a high sensitivityBiochemical tests should be performed at least twice.locali- sation of the phaeochromocytoma. MRI is preferred because contrast media used for CT scans can provoke paroxysms. Classically, phaeochromocytomas show a ‘Swiss cheese’ con- figuration.


123I-MIBG (metaiodobenzylguanidine) single-photon emission computed tomography (SPECT) will identify about 90 per cent of primary tumours and is essential for the detection of multiple extra-adrenal tumours and metastases. PET scanning using FDG PET or DOPA PET is yet more sensitive in detecting metastatic foci.

Treatment

Laparoscopic resection is now routine in the treatment of phaeochromocytoma. If the tumour is larger than 8–10 cm or radiological signs of malignancy are detected, an open approach should be considered

Preoperative Once a phaeochromocytoma has been diagnosed, an α-adrenoreceptor blocker (phenoxybenzamine) is used to block catecholamine excess and its consequences during surgery. WITH dequate medical pretreatment, the perioperative mortality rate has decreased from 20–45 per cent to less than 3 per cent

A dose of 20 mg of phenoxybenzamine initially should be increased daily by 10 mg until a daily dose of 100–160 mg is achieved and the patient reports symptomatic postural hypotension.β-blockade is required if tachycardia or arrhythmias develop; this should not be introduced until the patient is α-blocked.

Special attention is required when the adrenal vein is ligated as a sudden drop in blood pressure may occur. The infusion of large volumes of fluid or administration of noradrenaline can be necessary to correct postoperative hypotension in the presence of unopposed α-blockade.


Postoperative Patients should be observed for 24 hours in the intensive care or high dependency unit as hypovolaemia and hypoglycaemia may occur. Lifelong yearly biochemical tests should be performed to identify recurrent, metastatic or metachronous phaeochromocy- toma

Malignant phaeochromocytoma

Approximately 10 per cent of phaeochromocytomas are malignant. This rate is higher in extra-adrenal tumours (paragangliomas). The diagnosis of malignancy implies metastases of chromaffin tissue, most commonly to lymph nodes, bone and liver.

Symptomatic treatment can be obtained with α-blockers. Mitotane should be started as adjuvant or palliative treatment. Treatment with 131I-MIBG or combination chemotherapy has resulted in a partial response in 30 per cent and an improvement of symptoms in 80 per cent of patients. The natural history is highly variable with a five-year survival rate of less than 50 per cent.

Treatment

Surgical excision is the only chance for cure. Even in patients with metastatic disease, tumour debulking can be considered to reduce the tumour burden and to control the catecholamine excess.

ganglioneuroma 

Definition A ganglioneuroma is a benign neoplasm that arises from neural crest tissue. Ganglioneuromas can occur in the adrenal medulla characterised by mature sympathetic ganglion cells and Schwann cells in a fibrous stroma.

Clinical features

all age groups more common before the age of 60. anywhere along the paravertebral sympathetic plexus and in the adrenal medulla (30 per cent). Mostly identified incidentally by CT or MRI performed for other indications



Treatment
Treatment is by surgical excision, laparoscopic when adrenalec- tomy is indicated.

SURGERY OF THE ADRENAL GLANDS

Since its introduction in the 1990s, laparoscopic or retrop- eritoneoscopic adrenalectomy has become the ‘gold standard’ in the resection of adrenal tumours, except for tumours with signs of malignancy..

The mortality rate ranges from 0 to 2 per cent in specialised centres. In the case of small, bilateral tumours or in patients with hereditary tumour syndromes a subtotal resection is warranted, to avoid steroid dependence.


An open approach should be considered if: radiological signs, distant metastases, large tumours (>8–10 cm) or a distinct hor monal pattern suggest malignancy

Laparoscopic adrenalectomy