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Diagnosis and Treatment of Adrenal Tumors (Incidentaloma)

Definition

An adrenal incidentaloma is an (incidentally discovered) tumor of the adrenal gland. The most common cause is an adenoma without hormone production and without clinical significance. In 20%, a need for therapy arises from either progressive growth or hormone production.

CT of the abdomen showing a right-sided (=>) incidentaloma (histology: adrenal adenoma). The horizontal plane is on the left, and the frontal reconstruction is on the right. With kind permission, Prof. Dr. K. Bohndorf (Augsburg).

Pathology of Adrenal Incidentaloma

• Adenoma without hormonal activity (70%)
• Adenoma with cortisol secretion (10%)
• Adenoma with aldosterone secretion (6%)
• Pheochromocytoma (10%)
• Adrenocortical carcinoma (10%)
• Myelolipoma (8%)
• Cyst (5%)
• Ganglioneuroma (4%)
• Metastasis (7%)

Diagnosis of Adrenal Incidentaloma

A rational diagnostic workup of incidentaloma is shown in the flowchart below.

Algorithm for the diagnosis and treatment of adrenal incidentalomas, modified from (Langer et al., 2007).

Physical examination:

Hypertension? Tachycardia? Flushing symptoms? Hirsutism? Cushing disease? Virilization?

Imaging:

The diagnosis of an incidentaloma most commonly arises during imaging in case of complaints or during follow-up examinations of other diseases. CT characteristics of adrenal adenoma include evidence of fat in the tumor (native density of less than 10 HU); after contrast media, adenomas typically enhance. 15 min after contrast media, at least 60% of the enhancement should have disappeared. Contrast-enhancing lesions with native density values above 10 HU are suspicious for malignancy (Joudi et al., 2006). MRI is an alternative imaging technique and fat detection is possible with "chemical shift imaging"). For follow-up (size progression?), ultrasonography is also suitable.

Ultrasound imaging of the right retroperitoneum shows an 8 cm adrenal tumor. Histology: myelolipoma. The tumor's echogenicity indicates fat content. With kind permission, Dr. med. H. Kempter, Augsburg.

Hormone activity:

The hormone activity of adrenal tumor should be determined with blood tests and 24-hour urine collection:

• Serum: sodium, potassium, aldosterone, ACTH, cortisol, dexamethasone suppression test, DHEA, testosterone, androstenedione.
• 24-hour urine collection: sodium, epinephrine, norepinephrine, and catecholamine metabolism products (metanephrine and normetanephrine) in acidified urine. In a second unacidified urine collection over 24 hours: sodium, potassium, cortisol.
• Patients with hypertension: aldosterone/renin quotient in serum.
• Further tests depend on clinical suspicion and the results mentioned above.

Differential Diagnosis of Adrenal Tumors

• Adrenal adenoma
• Pheochromocytoma
• Adrenocortical carcinoma
• Rare benign tumors: hematoma, inflammatory tumors, ganglioneuroma, myelolipoma, lipoma, fibroma, adrenal cysts, oncocytoma.
• Neuroblastoma in children
• Lymphoma
• Metastases: mamma carcinoma, bronchial carcinoma, renal cell carcinoma, malignant melanoma, lymphoma.
• Tumors from neighboring organs such as kidneys, pancreas, spleen, bile ducts, vessels, and lymph nodes.

Active Surveillance and Treatment of Adrenal Tumors

A rational treatment for incidentaloma is shown in the flowchart above.

• Adrenal tumors <4 cm in size without hormone production: imaging once after one year if typical criteria for adrenal adenoma are present. If imaging becomes suspicious, additional imaging might be necessary. Annual check for hormone activity for four years. In case of size progression or hormone activity, adrenalectomy is indicated.
• Adrenal tumors 4–6 cm in size without hormone production: adrenalectomy or continue active surveillance (see tumors <4 cm size), depending on the patient's wishes, imaging results, and clinical situation.
• Adrenal tumors with hormone activity: adrenalectomy.
• Adrenal tumors larger than 6 cm: adrenalectomy.

References

Barzon und Boscaro 2000 BARZON, L. ; BOSCARO, M.: Diagnosis and management of adrenal incidentalomas.
In: J Urol
163 (2000), Nr. 2, S. 398–407

M. Fassnacht et al., “European Society of Endocrinology clinical practice guidelines on the management of adrenal incidentalomas, in collaboration with the European Network for the Study of Adrenal Tumors.,” European journal of endocrinology, vol. 189, no. 1, pp. G1–G42, Jul. 2023, doi: 10.1093/ejendo/lvad066.

Joudi u.a. 2006 JOUDI, Fadi N. ; KUEHN, David M. ; WILLIAMS, Richard D.: Maximizing clinical information obtained by CT.
In: Urol Clin North Am
33 (2006), Aug, Nr. 3, S. 287–300

  Deutsche Version: Inzidentalom der Nebennieren