Elliot K. Fishman M.D.
Johns Hopkins Hospital

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“Adrenal adenoma is the most common benign adrenal tumor that arises from the cortex, whereas adrenocortical carcinoma (ACC) is a rare malignant tumor of the cortex. Adrenal cyst and myelolipoma are other benign adrenal lesions and are characterized by their fluid and fat content, respectively. Pheochromocytoma is a rare neuroendocrine tumor of the adrenal medulla. Metastases to the adrenal glands are the most common malignant adrenal tumors. While many of these masses have classic imaging appearances,considerable overlap exists between benign and malignant lesions and can pose a diagnostic challenge.”
Adrenal Neoplasms: Lessons from AdrenalMultidisciplinary Tumor Boards
Ryan Chung et al.
RadioGraphics 2023; 43(7):e220191 July 2023

“More recent data have shown that these values are not as specific for adenoma as previously believed, since other adrenal tumors such as pheochromocytoma, hypervascular metastases, and ACC also can meet these washoutthresholds. Other features such as mass size, heterogeneity, and clinical context(eg, history of hypervascular malignancy or suspicion for pheochromocytoma)must be taken into account when using washout CT.”
Adrenal Neoplasms: Lessons from AdrenalMultidisciplinary Tumor Boards
Ryan Chung et al.
RadioGraphics 2023; 43(7):e220191 July 2023

“Because the attenuation of simple fluid is less than or equal to 10 HU, a homogeneousunilocular cystic adrenal lesion can mimic adenoma at nonenhancedCT. Owing to their central hypoattenuation, cysts and pseudocysts may also mimic pheochromocytomas with cystic and/or necrotic change. A key feature of an adrenal cyst is its lack of enhancement.”
Adrenal Neoplasms: Lessons from AdrenalMultidisciplinary Tumor Boards
Ryan Chung et al.
RadioGraphics 2023; 43(7):e220191 July 2023

“It may be impossible to distinguish a large atypical adenoma from an ACC or other malignant mass with imaging because of overlapping imaging features. If there are no benign diagnostic features, evaluation of the clinical context, including hormonal assessment, is essential for assessing the need for surgical resection of a 4-cm or larger adrenal mass. Patients with a large adrenal mass should be managedby a multidisciplinary team that includes surgeons, endocrinologists, and radiologists.”
Adrenal Neoplasms: Lessons from AdrenalMultidisciplinary Tumor Boards
Ryan Chung et al.
RadioGraphics 2023; 43(7):e220191 July 2023

“ Finally, it is important to recognize intense adrenal enhancement in morphologically normal-shaped adrenals, especially in unwell patients, because this finding may be an early sign of impending shock, warranting early critical-care management, and may also be a marker of poor prognosis in ill patients.”
Intense Adrenal Enhancement: A Feature of Hypoperfusion Complex
Venkatanarasimha N, Roobottom C
American Journal of Roentgenology. 2010;195: W82-W82

”Hypovolemic shock may be seen in trauma patients, and reduced blood volume typically prompts increased sympathetic activity, which can cause a constellation of findings on CT imaging, also known as the CT hypoperfusion complex. Hyperenhancing mesenteric vessels, decreased aortic caliber, slit-like IVC, intense enhancement of the kidneys, and dilated fluid-filled bowel loops are the findings of this complex .On imaging, shock adrenal glands demonstrate marked enhancement with preserved contours. Persistent, intense adrenal enhancement may be a sign of shock that precedes other imaging features of hypoperfusion, and similar findings were also observed in patients with severe acute pancreatitis.”
Cross‐sectional imaging features of unusual adrenal lesions: a radiopathological correlation 
Karaosmanoglu AD et al.
Abdominal Radiology (2021) 46:3974–3994

Is the mass actually an adrenal mass?

• Stomach
• Pancreas
• Retroperitoneal mass

“ The prevalence of adrenal incidentalomas has increased, and our result of 5% prevalence corroborates the 4.4% reported from a recent series compared with the 1-2% reported in the older literature.”
The Incidental Adrenal Mass on CT: Prevalence of Adrenal Disease in 1,049 Consecutive Adrenal masses in Patients with No Known Malignancy
Song JH et al.
AJR 2008; 190:1163-1168

“ In 973 consecutive patients with an incidental adrenal mass and no history of cancer, no malignant lesions were identified. Adenomas (75%) and myelolipomas (6%) were the most common lesions.”
The Incidental Adrenal Mass on CT: Prevalence of Adrenal Disease in 1,049 Consecutive Adrenal masses in Patients with No Known Malignancy
Song JH et al.
AJR 2008; 190:1163-1168

“ In conclusion, the results of our study show that none of the incidentally detected adrenal masses was malignant in patients with no known cancer. If an incidental adrenal mass appears benign on imaging and the patient has no known malignancy, follow-up imaging appears to have a limited role.”
The Incidental Indeterminate Adrenal Mass on CT (>10H) in Patients Without Cancer: Is Further Imaging Necessary? Follow-Up of 321 Consecutive Indeterminate Adrenal Masses
Song JH et al.
AJR 2007; 189:1119-1123

OBJECTIVE. The purpose of this study was to determine the rate of malignancy in incidentally detected bilateral adrenal masses in patients with no known history of cancer. 
CONCLUSION. No case of malignancy was found in 322 incidentally detected bilateral adrenal nodules at CT of patients without known cancer. Imaging follow-up of such lesions may be unnecessary. 
Incidentally Detected Bilateral Adrenal Nodules in Patients Without Cancer: Is Further Workup Necessary? 
Corwin MT et al.
AJR 2018; 210:780–784

“We found no cases of malignancy in 322 incidentally detected bilateral adrenal nodules at CT examinations of 161 patients who had no known cancer. Imaging follow-up of such lesions may be unnecessary.” 
Incidentally Detected Bilateral Adrenal Nodules in Patients Without Cancer: Is Further Workup Necessary? 
Corwin MT et al.
AJR 2018; 210:780–784

“Of 4085 patients with adrenal tumors, 705 (17%) had adrenal masses measuring 4 cm or more in diameter; of these, 373 (53%) were women, with a median age of 59 years (range, 18-91 years) and median tumor size of 5.2 cm (range, 4.0-24.4 cm). Underlying diagnoses were adrenocortical adenomas (n=216 [31%]), pheochromocytomas (n=158 [22%]), other benign adrenal tumors (n=116 [16%]), adrenocortical carcinomas (n=88 [13%]), and other malignant tumors (n=127 [18%]).”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors
Nicole M. Iñiguez-Ariza et al.
Mayo Clin Proc Innov Qual Outcomes. 2018 Mar; 2(1): 30–39.

”In conclusion, approximately one-third of radiologically proven adrenal adenomas in our retrospective single-institution study grew over time, at a rate of 3 mm/year or less, whereas malignant adrenal nodules grew at a faster rate, greater than 5 mm/year. If confirmed by larger multiinstitutional studies, a growth rate of 3 mm/year may be a useful threshold to distinguish benign from malignant adrenal nodules.”
Differences in Growth Rate on CT of Adrenal Adenomas and Malignant Adrenal Nodules 
Corwin MT et al.
AJR 2019; 213:1–5

“ In clinical practice therefore, 10 HU is the most widely used threshold value for the diagnosis of lipid-rich adrenal adenoma.”
Adrenal Imaging
Blake MA et al.
AJR 2010; 194:1450-1460

“Using a threshold of 10 HU on unenhanced images, a diagnosis of benign lipid-rich adenoma can be made with 98% specificity. However, lipid-poor benign adrenal nodules (approximately 20% of adenomas) measure greater than 10 HU on unenhanced CT but can be confidently diagnosed using contrast washout . Masses that have an absolute washout of ≥ 60% [(enhanced HU—delayed HU)/(enhanced HU—unenhanced HU)] or relative washout of ≥ 40% [(enhanced HU—delayed HU)/enhanced HU] are lipid- poor adenomas. Masses that have absolute washout of < 60% or relative washout of < 40% remain indeterminant and require further work-up.”
Management of incidental adrenal masses: an update 
Daniel I. Glazer, William W. Mayo‐Smith 
Abdom Radiol (NY). 2020 Apr;45(4):892-900.

“ Ten minute delayed multidetector CT adrenal washout tests have reduced accuracy compared with results from prior studies; overall test accuracy at 40% threshold was 77.7% according to our test results.”
Incidental Adrenal Lesions: Accuracy of Characterization with Contrast-enhanced Washout Multidetector CT—10-minute Delayed Imaging Protocol Revisited in a Large Patient Cohort
Sangwaiya MJ et al.
Radiology 2010; 256:504-510