Adrenal Incidentaloma1

Question 1

What percentage of abdominal and chest CT exams will identify an incidentaloma?

Answer 1

5%

Question 2

What is an adrenal incidentaloma?

Answer 2

Any adrenal mass 1cm or more in diameter discovered in a rediologic exam performed for indications other than adrenal disease.

Question 3

What is the prevalence of an adrenal incidentalomas?

Answer 3

Increases with age. It is less than 1% in people younger than 30 years and up to 7% in those older than 70 years.

Question 4

T/F: The concern for malignant potential is higher when larger lesions are found on younger patients.

Answer 4

TRUE

Question 5

T/F: The incidentalomas are most likely to be pheochromocytomas.

Answer 5

False. A recent review of more than 2000 incidentalomas identified nonfuctioning adenoma to be the most likely diagnosis (82%), followed by subclinical Cushing syndrome (5.3%), pheochromocytoma (5.1%), adrenocortical carcinoma (4.7%), metastatic disease (2.5%), and aldosteronoma (1.0%). Other infrequent disgnoses include adrenal cyst, hemorrhage, lymphoma, sarcoma, and neuroganglioma.

Question 6

Should all incidentalomas be evaluated for biochemical function?

Answer 6

Yes

Question 7

Which are the three most common secretory neoplasm?

Answer 7

Pheochromocytoma, Cortisol-producing adenoma, and Hyperaldosteronoma

Question 8

What percentage of essential hypertension is found to be due to hyperaldosteronism?

Answer 8

12%. All hypertensive patients should be screened.

Question 9

What is the most sensitive marker for pheochromocytomas?

Answer 9

Serum metanephrines and normetanephrines, which are the breakdown products of circulating catecholamines.

Question 10

T/F: Certain antihypertensives medications can cause elevation on the serum markers for pheochromocytomas.

Answer 10

True. Certain antihypertensives, including beta-blockers and ACE inhibitors, can contribute to elevations and shoul be discontinued if at all possible prior to retesting.

Question 11

What is the next step in diagnosing a pheochromocytoma if the serum metanephrines leaves the diagnosis of in doubt?

Answer 11

24 hour urine collection for metanephrines, catecholamines, and vanillylmandelic acid. Don’t order serum catecholamines as their rapid fluctuations render them useless.

Question 12

What is the next step in patients with bilateral incidentalomas and biochemical testing diagnostic of pheochromocytoma?

Answer 12

MIBG or MRI scan. Since less than 10% of pheochromocytomas are bilateral, there is a high chance that one of the incidentalomas is a benign cortical adenoma that may not require adrenalectomy.

Question 13

What is a cortisol-secreting adrenal incidentaloma?

Answer 13

Subclinical or preclinical Cushing Syndrome. It should not yet have produced the full phonotypic manifestations of Cushing disease/syndrome. More than 50% of this patients, may have hypeglycemia, hypertension, osteopenia, obesity, and fatigue but have not yet to develop the classic moon facies, buffalo hump, abdominal striae and advanced proximal muscle weakness diagnostic of Cushing disease/syndrome.

Question 14

What is the simplest method of screening for hypercortisolism?

Answer 14

Low-dose overnight dexamethasone suppression test, which is no more than 95 % sensitive.

Question 15

How is the low-dose overnight dexamethasone suppression test done?

Answer 15

The patient is prescribed 1mg of dexamethasone to be taken before bedtime on the night priorto a fasting morning blood sampling. The morning cortisol should suppress to less than 5ug/dL.

Question 16

What is the confirmatory testing for hypercortisolism if the cortisol does not suppress to less than 5ug/dL with a low-dose overnight dexamethasone suppression test?

Answer 16

24 hour urinary free cortisol

Question 17

What is the next test to order if hypercorticolism have been confirmed?

Answer 17

Serum adrenocorticotropic hormone (ACTH) level?

Question 18

What is the importance of the serum ACTH level after hypercortisolism have been confirmed?

Answer 18

Confirm that the source of excess cortisol is indeed the adrenal gland and not a pituitary or ectopic source of ACTH production.

Question 19

In which patients, a bilateral adrenalectomy may be warranted?

Answer 19

Bilateral, pigmented, micronodular adrenal hyperplasia is a rare cause of Cushing syndrome and is treated by bilateral laparoscopic adrenalectomy. Patients who would most benefit from aggressive treatment are those with end organ effects of hypercortisolism, including diabetes and osteoporosis. Some studies have suggested that unilateral adrenalectomy in these patients may sufficiently decrease cortisol levels so as to have a beneficial effect.

Question 20

Any patient with adrenal incidentaloma who also has hypertension or documented hypokalemia should be screen forﾅ

Answer 20

Primary hyperaldosteronism. Typical aldosteronomas are small (1 to 2 cm) and benign in appereance.

Question 21

What should be order to evaluate for hyperaldoteronism?

Answer 21

Serum aldosterone and plasma renin activity, followed by calculation of the aldosterone to plasma renin ratio. Patients are usually instructed to consume liberal salt diet during laboratory testing to prevent volume depletion, which normally elevates serum levels of renin and aldosterone.

Question 22

What aldosterone to plasma renin ration is suggestive of autonomous aldosterone secretion rather than hyperreninemia?

Answer 22

Ratio greater than 20 is considered positive for primary hyperaldosteronism.

Question 23

What is the confirmatory test for hyperaldosteronism?

Answer 23

24 urine aldosterone test.

Question 24

What percentage of hyperaldoteronism is caused by bilateral adrenal hyperplasia?

Answer 24

33%. So if contralateral adrenal is slightly enlarged, it too may be hypersecreting, or it could be even the sole source of aldosterone excess.

Question 25

What test can you perform to distinguish unilateral hypersecretion on a patient with bilateral adrenal masses?

Answer 25

Adrenal venous sampling which requires the simultaneous administration of IV ACTH while collecting aliquots of blood from both adrenals veins for aldosterone and cortisol levels.

Question 26

What characteristic about an incidentaloma will help you determine the malignant potential?

Answer 26

Size. For lesions smaller than 4 cm, less than 2 % will prove to be adrenocortical carcinoma, as opposed to more than 20% of lesions 6cm in diameter or larger.

Question 27

What is an essential step in evaluating an adrenal incidentaloma?

Answer 27

Locate previous imaging studies that would have included the adrenals?

Question 28

What is the malignant potential of an adrenal mass with no significant change in size over a 2-year period or longer?

Answer 28

Extremely low, even for lesions greater than 4cm.

Question 29

What imaging characteristics are suspicious for malignant adrenal incidentalomas?

Answer 29

Large, heterogenous, irregular lesions and those that invade surrounding structures.

Question 30

What imaging characteristics are suspicious for benign adrenal incidentalomas?

Answer 30

Small, homogenous and well-defined

Question 31

What important information is obtained from imaging about incidentalomas?

Answer 31

Size, contour, complexity, presence of calcification and necrosis and the Hounsfield unit (HU) density.

Question 32

What are the HU units and how they correlate with malignant adrenal incidentalomas?

Answer 32

HU densities vary depending on the intracellular lipid concentration of a tissue. Lipid-rich benign adenomas generally have low HU densities (<18), whereas pheochromocytomas and malignancies contain few lipids and typically measure higher. Radiologist can predict with 98% specificity the benign nature of an incidentaloma if the unenhanced HU density is less than 10; if not biochemically active such lesions can generally be followed radiographically.

Question 33

How immediate and 15 minute delayed CT scan images help in the diagnosis of benign vs malignant adrenal adenomas?

Answer 33

The most commonly used criteria for establishing an adrenal neoplasm as a benign adenoma is a 15-minute delay washout ratio of 40% or more. Lesions demonstrating less than 40% washout should be considered suspicious for malignancy. Accuracy of this technique has been confirmed for both lipid-rich and lipid-poor adenomas, with both sensitivity and specificity greater than 90% when evaluated by radiologists specializing in the interpretation of such scans.

Question 34

What advantages has the MRI over the CT scan when evaluating adrenal masses?

Answer 34

MRI provides the advantages of imaging without radiation, is useful for patients with iodine contrast allergies, has excellent contrast resolution for tissue characterization, and is superior to CT for identifying invasion of adrenal carcinomas into adjacent organs. Generally, primary and metastatic adrenal malignancies are denser than benign adenomas because of their higher fluid content and therefore appear brighter on T2-weighted images. This is also true of pheochromocytoma.

Question 35

What is a MIBG scan?

Answer 35

Metaiodobenzylguanidine (MIBG) scan is highly sensitive and specific for identification of pheochromocytoma.

Question 36

What is the role of adrenal biopsy?

Answer 36

Adrenal biopsy is rarely helpful or indicated in the evaluation of adrenal incidentaloma. It often will have produced periadrenal hemorrhage with associated inflammatory change and obliteration of the normal tissue planes, increasing the difficulty of dissection and potential for surgical morbidity. The only clinical situations in which it proves helpful are in diagnosing adrenal metastatic disease in patients known to have, or suspected of having, melanoma, lymphoma, or extraadrenal cancer such as lung, renal cell, breast, or gastrointestinal cancer.

Question 37

Who should have an adrenalectomy?

Answer 37

In general, all hormone-secreting adrenal neoplasms require resection. In the era preceding laparoscopic adrenalectomy, the generally accepted size threshold for adrenalectomy was 6 cm, with a risk for ACC approaching 20%. Today, most endocrine surgeons who perform laparoscopic adrenalectomy employ a 4 cm size threshold, below which the risk for ACC is less than 2%. However, when the imaging phenotype can definitively characterize lesions as benign despite larger diameters, it may be acceptable to follow a nonoperative management strategy.

Question 38

T/F: Before proceeding with adrenalectomy, you donﾒt need to confirm that the contralateral gland is normal.

Answer 38

False. Before proceeding with adrenalectomy, always confirm that the contralateral gland is normal.

Question 39

What are the advantages of laparoscopic adrenalectomy?

Answer 39

Compared with open adrenalectomy, laparoscopic adrenalectomy is proven to result in less blood loss and decreased need for transfusion, fewer wound complications, decreased postoperative pain, and shorter hospitalizations. Although the technical difficulty of performing laparoscopic adrenalectomy increases with increasing tumor size, uncomplicated resection of lesions larger than 10 cm in diameter has been reported.

Question 40

Who should have an OPEN adrenalectomy and why?

Answer 40

An open approach should be considered for any lesions that demonstrate features worrisome for malignancy, such as rapid growth, areas of necrosis, or possible invasion of adjacent structures. Open resection remains the gold standard for suspected adrenocortical carcinoma to ensure an oncologically correct operation that maximizes the chances of a margin-negative resection; avoids violation of the tumor capsule and tumor spillage; facilitates vascular control of the inferior vena cava, aorta, and renal vessels; and allows maximal exposure for en bloc resection of associated anatomic structures.

Question 41

What preoperative preparation is needed for a patient with pheochromocytoma?

Answer 41

For patients with pheochromocytoma, alpha blockade should begin with phenoxybenzamine 10 mg daily and be titrated to 10 mg three times daily over 3 weeks, after which time adrenalectomy can be safely performed . The main side effects of this treatment will be orthostatic hypotension, fatigue, and sinus congestion. Pheochromocytoma induces diuresis and volume depletion, so patients must be adequately hydrated before and during surgery. Beta blockade is not recommended, unless patients are persistently tachycardic.

Question 42

What is important to remember postoperatively on patients with cortisol hypersecretion?

Answer 42

Patients with cortisol hypersecretion will become adrenally insufficient in the immediate postoperative period, requiring perioperative stress-dose steroids and often a prolonged steroid taper at the time of discharge.

Question 43

Which two approaches can you use for a laparoscopic adrenalectomy?

Answer 43

Tansabdominal approach with the patient in the lateral decubitus position or via a retroperitoneal approach with the patient prone on a Wilson frame.

Question 44

Which advantages has the retroperitoneal approach?

Answer 44

Useful in patients with small tumors and in those who are expected to have significant peritoneal adhesions from previous operations. It avoids the need for mobilization of the colon, spleen, and liver that is employed in the transabdominal approach. It is also an excellent choice when bilateral adrenalectomy is required. However, because of the small retroperitoneal working space, limitations to its use include very large tumors and morbidly obese patients.

Question 45

How can you get access laparoscopically to the left adrenal?

Answer 45

The lateral attachments of the spleen should be mobilized with the harmonic scalpel up to the level of the gastric fundus. Full mobilization allows the spleen to fall medially, pulling the tail of the pancreas with it, allowing for better adrenal exposure. Pancreatic tissue is similar in appearance to adrenal tissue and should be avoided.

Question 46

How can a laparoscopic ultrasound be helpful during a laparoscopic adrenalectomy?

Answer 46

Judicious use of laparoscopic ultrasound will quickly clarify the borders of the adrenal, kidney, and pancreas on the left and the liver, kidney, and major vessels on the right, allowing for safe and expeditious dissection, especially when there is abundant retroperitoneal fat.

Question 47

What is the estimated 5-yr risk of incidentaloma enlargement and hyperfunction?

Answer 47

20%

Question 48

After an incidentaloma is detected, how long should a patient be screen for pheochromocytoma or cortisol secretion?

Answer 48

Up to 3 years after an incidentaloma is first detected.

Question 49

What is the appropriate long term follow up of small, nonfunctional incidentalomas?

Answer 49

In a patient with a tumor less than 4 cm and no radiographic suggestion of malignancy, annual CT scan should be performed for 2 to 3 years. If there is no change, it is generally safe to assume that the lesion will remain benign.

Question 50

How can you follow up a small nonfunctional incidentaloma suspicious for malignancy on imaging?

Answer 50

Repeat CT is recommended at 3, 6, and 12 months if the radiographic characteristics raise suspicion of possible malignancy, as the growth rate for adrenocortical cancer is expected to be more than 2 cm per year. Lesions that enlarge more than 1 cm in follow-up should be removed.