A 22-year-old female comes with an incidentally detected mass in the right adrenal gland of 2 cm size detected during a CT scan done for abdominal pain. She has no hypertension, no cushingoid features and no virilization. She has no family history of multiple endocrine neoplasia. She has no history of renal calculi. The cause of abdominal pain is finally diagnosed as abdominal migraine. How will you evaluate this case of adrenal incidentaloma? An adrenal “incidentaloma” is an adrenal mass, generally 1 cm or more in diameter that is discovered ‘incidentally’ during a radiologic examination performed for indications other than an evaluation for adrenal disease. The definition of incidentaloma excludes patients undergoing imaging procedures as part of staging and work-up for cancer and patients with symptomatic adrenal disease not elicited due to oversight. Adrenal incidentaloma is not a single entity; rather it is an ‘umbrella’ defini-tion comprising a spectrum of different pathological entities that share the same path of discovery. The widespread use of computed tomography (CT), diagnostic ultrasound, and magnetic resonance imaging (MRI) has resulted in the frequent incidental discovery of asymptomatic adrenal masses. The optimal diagnostic approach to a patient who has an adrenal incidentaloma is by taking a careful history and performing a physical examination, focusing on the signs and symptoms suggestive of adrenal hyperfunction or malignant disease followed by hormonal testing, when indicated. The two important questions to be answered at the end of evaluation are:
• Does the patient have a lesion suggestive of malignancy?
• Is the lesion hormonally active?
• Do you want any further information from the CT scan done?
How do characteristic features on radiological imaging help in the evaluation of adrenal incidentaloma?
Medicine
Advances in modern imaging have made it a powerful ally in delineating benign from malignant processes in AIs. Certain characteristic features on imaging will help to distinguish among adrenal adenoma, adrenal carcinoma, pheochromocytoma, and metastatic lesions. It is important to emphasize that imaging cannot reliably distinguish between functioning and nonfunctioning adrenal adenomas as shown in Table 13.1.
• The size of the mass and its appearance on imaging are the two major predictors of malignant disease.
• Size of adrenal mass: Diameter greater than 4 cm was shown to have 90% sensitivity for the detection of adrenocortical carcinoma but nondiagnostic of malignancy as only 24% of lesions greater than 4 cm in diameter were malignant. Also a size less than 4 cm does not rule out malignancy.
• Imaging phenotype: CT features used to distinguish adenomas from nonadenomas are the lipid content of the adrenal mass and rapidity of the washout of contrast medium.
– The intracytoplasmic fat in adenomas results in low attenuation on unenhanced CT, nonadenomas have higher attenuation on unenhanced CT. Lesions that have an attenuation value below 10 HU on noncontrast CT scan are adenomas. That being said, it is important to remember that the lipid poor variants of adenomas will have higher attenuation on unenhanced CT.
– On contrast study, benign adrenal lesions will commonly enhance up to 80–90 HU and washout more than 50% on the delayed scan, whereas lesions such as metastatic tumors, carcinomas, or pheochromocytomas
will not. If unenhanced CT or CSI is indeterminate, contrast enhanced CT with washouts at 10 to 15 minutes has been shown to have excellent sensitivity and specificity, approaching 100%, in differentiating between adenomas and nonadenomatous incidentalomas.
• Characteristics of pheochromocytoma and malignant processes include size (>3 cm), attenuation of >10 HU on unenhanced CT, heterogeneous texture and increased vascularity with decreased contrast washout at 10–15 minutes.
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