An adrenal cyst is a fluid-filled sac that develops on one of the adrenal glands. These small, triangular-shaped glands are located on top of each kidney in the back of the abdomen. Adrenal glands produce various hormones that regulate functions such as blood pressure, metabolism, and the body’s response to stress. Adrenal cysts are considered rare, and the vast majority of them are non-cancerous.
Causes and Types of Adrenal Cysts
The precise reason why adrenal cysts form is often not fully understood; many are considered to be idiopathic, meaning they arise without a known cause. However, these cysts can be broadly categorized based on their cellular origin and composition. The most frequently encountered types include endothelial cysts, pseudocysts, and epithelial cysts.
Endothelial cysts originate from the lining of blood or lymphatic vessels within the adrenal gland. Pseudocysts, in contrast, lack a true cellular lining and are thought to develop from a previous hemorrhage or trauma within the adrenal gland.
Epithelial cysts, which are less common, arise from glandular tissue and constitute about 9% of adrenal cysts. Extremely rare are parasitic cysts, typically caused by an infection with the Echinococcus granulosus parasite, which accounts for around 7% of cases globally.
Associated Symptoms and Potential Complications
Most adrenal cysts do not cause any noticeable symptoms and are discovered by chance. When symptoms do occur, they are associated with larger cysts that exert pressure on nearby organs. Individuals might experience flank or abdominal pain, a sensation of fullness in the abdomen, or digestive issues such as nausea or constipation.
In a small number of cases, an adrenal cyst can be “functional,” meaning it produces an excess of adrenal hormones. This hormonal overactivity can lead to symptoms like high blood pressure, headaches, muscle weakness, or fatigue. Serious complications can arise, including bleeding into the cyst (hemorrhage) or a sudden rupture, which may cause acute abdominal pain and a dangerous drop in blood pressure.
How Adrenal Cysts Are Diagnosed
Adrenal cysts are often discovered incidentally during imaging tests performed for unrelated medical conditions, a finding referred to as an “incidentaloma.” Medical imaging techniques are the primary tools used to identify and characterize these cysts.
Computed tomography (CT) scans, magnetic resonance imaging (MRI), and ultrasound are employed to visualize the adrenal glands. These imaging modalities can provide detailed information about the cyst’s size, location, and its internal characteristics, such as whether it contains clear fluid or has calcifications. To determine if a cyst is hormonally active, doctors may also order specialized blood and urine tests. These tests measure the levels of various adrenal hormones to identify any excessive production.
Management and Treatment Options
The approach to managing an adrenal cyst depends on its size, whether it causes symptoms, if it produces hormones, and its appearance on imaging. For small adrenal cysts that are not causing symptoms or producing hormones, observation, often termed “watchful waiting,” is recommended. This involves periodic follow-up imaging, such as CT or MRI scans, to monitor for any changes in size or characteristics.
Surgical removal of the adrenal gland containing the cyst, a procedure known as adrenalectomy, is considered when certain criteria are met. This includes cysts that are large, typically exceeding 5 to 6 centimeters in diameter, or those that are causing symptoms like pain or abdominal discomfort. Surgery is also advised for cysts that are found to be hormonally active or those that show suspicious features on imaging, which might suggest a more aggressive nature. Following treatment for benign adrenal cysts, the outlook for recovery is favorable.