The adrenal glands are small, triangular organs situated immediately above each kidney. They consist of the outer cortex and the inner medulla, which produce hormones regulating metabolism, blood pressure, and the body’s stress response. An adrenal mass is any abnormal growth, lump, or tumor found within one or both glands. While finding a mass often prompts concern, many are non-cancerous and do not produce excess hormones.
Common Types of Adrenal Masses
The identity of an adrenal mass is defined by the type of cells it originates from, determining whether it is benign or malignant. Adrenal adenomas are the most frequent type, representing a non-cancerous tumor developing from the adrenal cortex. These masses are typically small and often found incidentally during imaging performed for unrelated health issues.
A much less common but more serious type is adrenocortical carcinoma (ACC), a highly aggressive cancer that also arises in the adrenal cortex. A pheochromocytoma is a tumor that develops from chromaffin cells in the adrenal medulla. While most pheochromocytomas are benign, they are significant because they frequently overproduce powerful hormones.
The adrenal glands can also be a location for metastases, which are cancerous cells that have spread from a primary tumor located elsewhere in the body. Understanding the cell origin is the first step in assessing the risk, but the mass’s hormonal activity dictates the immediate threat to health.
Functional Versus Non-Functional Activity
The most telling factor in assessing an adrenal mass is whether it is functional, meaning it produces excessive hormones, or non-functional, meaning it is hormonally silent. Approximately 75% of adrenal masses are non-functional and do not cause symptoms unless they grow large enough to press on nearby organs. These non-functional masses, often adenomas, are considered low-risk and may require only monitoring.
Conversely, a functional mass disrupts the body’s hormonal balance, making it a health concern regardless of its size. Excess production of cortisol can lead to Cushing’s Syndrome, characterized by weight gain, easy bruising, and high blood sugar. Overproduction of aldosterone, which regulates salt and water balance, causes Conn’s Syndrome (primary aldosteronism), often resulting in difficult-to-control high blood pressure.
A pheochromocytoma can secrete excessive amounts of catecholamines, such as adrenaline, leading to unpredictable and dangerous hypertensive crises. These hormone-producing masses, even if benign, pose a serious risk for cardiovascular complications, including stroke and heart disease. Therefore, the functionality of the mass is the primary driver for urgent intervention.
The Diagnostic Process
Adrenal masses are frequently discovered incidentally during abdominal imaging (CT or MRI) performed for other reasons, a finding known as an adrenal incidentaloma. The initial imaging assessment provides crucial information about the mass’s physical characteristics. Low-density measurements (less than 10 Hounsfield Units on a non-contrast CT scan) strongly suggest a benign, lipid-rich adenoma.
Radiologists also evaluate the mass’s “washout” rate—how quickly contrast dye leaves the tissue—to distinguish benign tumors from more suspicious lesions. The size of the mass is also measured, as growths larger than four centimeters are associated with a higher risk of malignancy. However, imaging alone cannot determine if a mass is functional.
To check for hormonal activity, a comprehensive biochemical workup is performed before any surgical decisions are made. This involves specialized blood tests and 24-hour urine collections to measure levels of cortisol, aldosterone, and catecholamines. This identifies even subtle hormonal overproduction.
Treatment and Long-Term Monitoring
Once the mass is fully characterized, a treatment plan is established. For small, non-functional masses showing benign characteristics, the standard approach is active surveillance, or “watchful waiting.” This involves repeat imaging and hormone testing at regular intervals (e.g., six months after discovery, then annually) to monitor for growth or new hormonal activity.
Surgical removal of the adrenal gland (adrenalectomy) is recommended when the mass is functional, malignant, or exceeds a high-risk size threshold (typically four to six centimeters). Removing a functional mass eliminates the source of hormone overproduction, resolving the associated health risks.
Patients with a pheochromocytoma must undergo pre-surgical medication to block the effects of the excess catecholamines. This preparation stabilizes blood pressure and prevents life-threatening complications, such as a severe hypertensive crisis, that could be triggered during the surgery.