Radiographic Evaluation

Adrenal tumors are frequently diagnosed, with incidental adrenal tumors found in 3.4% to 7.0% of patients on imaging studies. Although adrenal masses were historically diagnosed based on sequelae from hormone-secreting tumors, most masses are now found based on imaging alone. Meaningful clinical information may be gleaned from the imaging evaluation. Besides size, which can drive surgical management, enhancement characteristics can help differentiate adenomas from other lesions. Hamrahian and colleagues, from the Cleveland Clinic, evaluated 290 patients and found that adrenal adenomas had significantly lower mean Hounsfield unit (HU) attenuation (16.2) than ACC (36.9), adrenal metastases (39.2), or pheochromocytoma (38.6). The high intracytoplasmic fat content of adenomas causes this difference in attenuation. Furthermore, a cutoff of 10 HU was associated with a 100% specificity to differentiate adenomas from nonadenomas, though the sensitivity was only 40%. Therefore, although lesions with 10 HU or less are almost universally adenomas, lesions with greater than 10 HU attenuation may require further evaluation, as 30% of adrenal adenomas are fat poor. In these cases, the pattern of intravenous contrast washout can be helpful. Adenomas have faster washout of enhancement than other lesions like metastases or pheochromocytomas, which retain contract for longer periods. A washout of 40% to 60% at 10 min is typical of adenomas, with specificity approaching 100%.

Although computed tomography (CT) studies can identify most adrenal adenomas, magnetic resonance imaging (MRI) can also be a useful adjunct. In opposed-phase MRI, lesions with intracellular lipid may be identified by loss of signal intensity on out-of-phase images.

Hypercortisolism

Hypercortisolism, or Cushing syndrome, is characterized by excess circulating glucocorticoid. The signs and symptoms of hypercortisolism include hypertension, truncal obesity, moon facies, hirsutism, mood disturbance, osteopenia, diabetes mellitus, and easy bruising. Although there are multiple causes of Cushing syndrome, including exogenous steroid use and corticotropin-secreting pituitary tumors, the cause germane to this review is a cortisol-secreting adrenal tumor. The simplest screening test recommended by the AACE/AAES is the 1-mg overnight dexamethasone suppression test. In patients with clinical suspicion because of hypertension, obesity, diabetes, or osteoporosis, 3 tests including the late-night salivary cortisol and urine-free cortisol in addition to the dexamethasone suppression test may be administered to confirm the diagnosis.

Primary Aldosteronism

Primary aldosteronism, or Conn syndrome, is characterized by elevated serum aldosterone levels. Hyperaldosteronism results in increased total-body sodium, which causes hypertension and sometimes mild hypernatremia, as well as decreased potassium, which can cause muscle weakness and paresthesias. Standard laboratory evaluation may reveal hypernatremia and hypokalemia, although these may be masked by drugs including potassium-sparing diuretics. Screening for hyperaldosteronism should be performed in patients with adrenal lesions and hypertension, and screening can be omitted in patients without hypertension. Before screening, hypokalemia should be corrected; mineralocorticoid receptor antagonists should be stopped at least 6 weeks before screening. Screening is performed by obtaining an aldosterone-to-renin ratio (ARR). An ARR greater than 20 suggests hyperaldosteronism, which can be confirmed by demonstrating a lack of aldosterone suppression with salt loading on a 24-hour urine study. A high-resolution CT scan can distinguish aldosteronomas from adrenal hyperplasia in many people; but aldosteronomas may be very small and not always readily apparent. In these cases, and in most patients older than 40 years, adrenal vein sampling is recommended to lateralize the lesion.

Pheochromocytoma

Pheochromocytoma is a catecholamine-producing tumor of the adrenal medulla. Symptoms include hypertension, headache, diaphoresis, and tremor. Screening for pheochromocytoma should include the measurement of plasma fractionated metanephrines and normetanephrines or 24-hour total urinary metanephrines. Additionally, genetic counseling should be offered, as up to 25% of patients with pheochromocytoma has associated familial syndrome, including von Hippel-Lindau, multiple endocrine neoplasia type 2, neurofibromatosis type I, or succinate dehydrogenase mutations.

Positioning, Approach, and Port Placement

Patients are placed in the modified left or right flank position with the side of the lesion facing up. All pressures points are carefully padded with a combination of pillows and foam, and patients are secured to the surgical table with tape. The patients’ arms are placed in a mildly flexed position either over a double arm board or tucked next to the body.

Multiple surgical approaches have been described to access the adrenal gland, but the 2 most common approaches are the lateral transabdominal adrenalectomy (LTA) and the posterior retroperitoneoscopic adrenalectomy (PRA).

LTA is the most common transperitoneal approach. This approach allows greater working space than the retroperitoneal approach, which can be beneficial for larger tumors and obese patients. Patients are placed in the flank position with the side of the tumor facing up, allowing gravity to retract the abdominal contents medially.

LTA port placement is illustrated in Fig. 1 . After initiating pneumoperitoneum with a Veress needle, a 12-mm camera port is placed superolateral to the umbilicus. Next, two 8-mm robotic ports are placed under vision, 1 below the costal margin at the later border of the rectus and the other cephalad to the anterosuperior iliac spine. All robotic ports should have at least 8 cm of distance between them to prevent clashing. A 12-mm assistant port is place between the camera port and lower robotic port. For right-sided cases, a 5-mm port can be placed below the xiphoid process to place a liver retractor. Finally, the robot is docked coming over the patients’ ipsilateral shoulder.

Port placement for ( A ) left-sided and ( B ) right-sided robotic adrenalectomy.

PRA is the most common retroperitoneal approach. This approach allows avoidance of entering the peritoneal cavity, which may be beneficial in patients with prior abdominal surgery. However, there is often less working room and anatomic landmarks may be unfamiliar compared with the transperitoneal view. Access to the retroperitoneum is gained inferolateral to the tip of the 12th rib by perforation the dorsal lumbar fascia and with finger dissection of the retroperitoneal space. Next, two 8-mm incisions for the robotic working arms are made medial and lateral to the camera port with finger guidance to ensure they are positioned in the retroperitoneum. A balloon can be used to dissect and inflate the retroperitoneal space; the ports are placed; and the robotic is docked.

In a systematic review and meta-analysis comparing LTA and PRA during laparoscopic adrenalectomy, there was no difference in operative time, blood loss, time to ambulation, oral intake, or complication rate between techniques, with equivocal findings for hospital length of stay (LOS) and convalescence time. A more recent meta-analysis found no difference in any perioperative outcome, including operative time, blood loss, hospital stay, time to oral intake, overall and major morbidity, and mortality.