Most cysts found on the adrenal gland are benign, slow-growing, and unlikely to cause problems. Across large imaging studies, adrenal cysts account for only about 1% of all adrenal masses discovered incidentally, and roughly 7% of those cysts turn out to be malignant or have malignant potential. That leaves the vast majority as harmless fluid-filled sacs that a person may carry for years without knowing. Still, the word “cyst” on an imaging report understandably raises alarm, and the answer to whether yours deserves concern depends on its type, size, imaging features, and whether it produces hormones or symptoms.
How Adrenal Cysts Are Typically Discovered
Adrenal cysts almost never announce themselves. They are usually spotted by accident when a CT scan, MRI, or ultrasound is ordered for an unrelated reason, such as abdominal pain, kidney stones, or staging for a cancer workup. Doctors call any unexpected adrenal finding an “incidentaloma.” Adrenal incidentalomas as a group show up on roughly 0.5–2% of abdominal CT scans, and at autopsy the prevalence is even higher, around 2.3%.1European Journal of Endocrinology. Prevalence and natural history of adrenal incidentalomas Among those incidentalomas, though, true cysts are uncommon. In one large series of over 1,000 consecutive adrenal masses in patients without known cancer, cysts made up just 1% of the total; adenomas accounted for 75%, and myelolipomas another 6%.2PubMed. The incidental adrenal mass on CT: prevalence of adrenal disease in 1,049 consecutive adrenal masses in patients with no known malignancy So if you have been told you have an adrenal cyst, you are dealing with something fairly unusual to begin with.
The Four Types of Adrenal Cyst
Not all adrenal cysts are the same under a microscope, and the type matters for prognosis. Pathologists group them into four categories based on what lines the cyst wall and how the cyst likely formed.3PubMed. Diagnosis and treatment of the adrenal cyst
- Endothelial cysts: The most common type, making up about 45% of adrenal cysts. These are lined by cells that normally form blood or lymph vessels. A subgroup called lymphangiomatous cysts likely arises from dilated and clotted lymphatic channels. Endothelial cysts are almost always benign.
- Pseudocysts: Roughly 39% of cases. Unlike true cysts, pseudocysts lack an inner lining of specialized cells. Evidence suggests they form after bleeding inside the adrenal gland, essentially organizing around old hemorrhage. They are usually benign, but pseudocysts have the strongest association with hidden tumors among the four types.
- Epithelial cysts: About 9%. These are lined by glandular cells and are generally harmless.
- Parasitic cysts: Around 7%. Almost all are caused by the hydatid tapeworm (Echinococcus). These are mainly a concern in regions where the parasite is common, such as parts of the Mediterranean, Middle East, South America, and Central Asia.
Distinguishing between these types usually requires surgery and a pathology report, because imaging alone cannot always tell them apart.4PubMed Central. Endothelial cyst of the adrenal gland: A rare case report
When an Adrenal Cyst Causes Symptoms
Most adrenal cysts produce no symptoms at all. Pain or discomfort tends to show up only when a cyst grows large enough to press on surrounding structures, or when it bleeds internally. Large pseudocysts, for instance, can push against the kidney, stomach, or diaphragm and cause a dull ache in the flank or upper abdomen.5PubMed Central. Spontaneous rupture and hemorrhage of adrenal pseudocyst presenting with acute abdomen and shock
One interesting exception involves endothelial cysts of the lymphangiomatous subtype. These have been linked to back pain, flank pain, or hypertension in a surprisingly high proportion of cases, with pain reported in nearly half and hypertension in about 14%, even when the cysts are relatively small and show no sign of having bled. The exact reason is not well understood; proposed explanations include irritation of surrounding tissue, local inflammation, or abnormal lymphatic drainage, but the mechanism remains an open question.6Endocrine Abstracts. The Adrenal that inCYSTS on causing pain If you have unexplained flank pain alongside an adrenal cyst, that connection is worth raising with your doctor even if the cyst looks small on imaging.
How Often Are Adrenal Cysts Cancerous?
The overall malignancy rate for adrenal cysts is low. A widely cited surgical series found that only about 7% of adrenal cysts were malignant or had malignant potential, and only one reported case involved a cancer discovered in a cyst that was initially thought to be entirely benign.7The American Surgeon. Management of Adrenal Cysts That is reassuring, but it is not zero, and the risk is not spread evenly across cyst types.
Pseudocysts carry the highest concern. In a surgical series of 41 cystic adrenal lesions, 6 of the 32 pseudocysts were found alongside a hidden tumor, including two adrenal cortical carcinomas (both patients ultimately died of the disease), two benign adenomas, and two pheochromocytomas. One pheochromocytoma also turned up with an endothelial cyst.8PubMed. Cystic adrenal neoplasms The takeaway is not that pseudocysts are likely to be cancerous, but that they deserve extra scrutiny compared with simple endothelial or epithelial cysts.
What Imaging Can and Cannot Tell You
When a cyst shows up on a CT scan, doctors look at several features to judge how worried they should be. A simple, benign-looking cyst typically has thin walls (3 mm or less), uniform low density on CT (below about 20 Hounsfield units, which is close to water), no solid internal components, and no enhancement after contrast dye is injected. In one CT study of cystic adrenal lesions, benign cysts had walls 3 mm or less in 31 of 37 cases, whereas one of the three cysts with thick walls exceeding 6 mm turned out to be a cystic carcinoma.9PubMed. Cystic adrenal lesions: CT features
MRI can add useful detail, especially when CT findings are unclear. Fluid inside a cyst produces characteristic signal patterns on MRI. In a long-term imaging study, cysts were confirmed by lack of enhancement on CT or MRI in most patients, and MRI showed typical fluid signals in every case examined.10PubMed. Adrenal cysts: natural history by long-term imaging follow-up Ultrasound can also help distinguish a simple cyst from something more complex, though it is less commonly the first test ordered.
Features that raise a red flag include thick or irregular walls, internal septations (dividing walls), solid nodules within the cyst, high density on CT, and enhancement of the cyst wall or contents after contrast. None of these features alone means cancer, but they shift the probability enough that further investigation, sometimes including surgery, becomes worthwhile.
How Fast Do They Grow?
One of the most practical questions after being told you have an adrenal cyst is whether it will keep growing. The data here is reassuring. A study following 92 patients with benign adrenal cysts over a median of about five and a half years found minimal enlargement, with a median size increase of just 6 mm over the entire follow-up period, translating to roughly 2 mm per year.11European Journal of Endocrinology. Clinical course and imaging characteristics of benign adrenal cysts: a single-center study of 92 patients That rate is slow enough that many cysts can be safely watched with periodic imaging rather than immediately operated on. Rapid growth on serial scans, by contrast, would prompt closer evaluation.
Complications Worth Knowing About
The rare but serious complication of an adrenal cyst is rupture, which can cause sudden hemorrhage into the space behind the abdominal organs. This typically produces sharp, acute abdominal pain, and in severe cases can lead to hemorrhagic shock requiring emergency surgery. Published reports describe this happening both spontaneously and after blunt abdominal trauma. In one case, a 21-year-old woman presented with sudden abdominal pain and shock from spontaneous rupture of a pseudocyst and needed emergency open surgery with removal of the cyst and the affected adrenal gland.5PubMed Central. Spontaneous rupture and hemorrhage of adrenal pseudocyst presenting with acute abdomen and shock Another report described massive retroperitoneal hemorrhage after blunt trauma ruptured an adrenal cyst.12PubMed. Massive retroperitoneal hemorrhage owing to a ruptured adrenal cyst
Rupture is genuinely rare, and the risk is higher with larger cysts. This is one of the practical reasons doctors consider removal when a cyst reaches a certain size, even if it looks benign on imaging. A large cyst sitting in the retroperitoneum is a fragile structure, and the consequences of rupture are serious enough to justify preventive surgery in some cases.
When Surgery Is Recommended
There is no universally agreed-upon size cutoff that automatically triggers surgery, but several factors push the decision in that direction. Large size (often above 5–6 cm), symptoms such as pain or compression of nearby organs, worrisome imaging features, hormone production, and growth on serial scans are all reasons a surgeon may recommend removal. When a cyst cannot be confidently distinguished from a cystic tumor, surgery serves both therapeutic and diagnostic purposes, because the pathology report after removal is the only way to get a definitive answer.
The good news is that most adrenal cyst surgery today is done laparoscopically, through small incisions. In a series of eight patients who underwent laparoscopic surgery for symptomatic or large cysts, the average operation took about 78 minutes, the average hospital stay was under two days, and there were no surgical complications. At follow-up of roughly 18 months, all patients were symptom-free with no cyst recurrence on imaging.13PubMed. Laparoscopic management of symptomatic and large adrenal cysts Depending on the situation, surgeons may remove the entire adrenal gland, remove the cyst along with part of the gland, or simply unroof (decorticate) the cyst. Losing one adrenal gland is generally well tolerated because the opposite gland picks up the hormonal workload.
Sclerotherapy as a Non-Surgical Alternative
For patients with benign-appearing symptomatic cysts who want to avoid surgery, percutaneous aspiration and sclerotherapy is an emerging option. The procedure involves draining the cyst through a needle inserted under image guidance and then injecting an agent like ethanol to collapse the cyst wall and prevent refilling. In a small series of three patients treated with single-session ethanol sclerotherapy, compressive symptoms resolved in all of them, and the cysts shrank by over 98% with no recurrence at follow-up intervals ranging from about six months to nearly a year and a half. Side effects were limited to mild temporary retroperitoneal pain in two patients.14Journal of Vascular and Interventional Radiology. Single-Session Ethanol Sclerotherapy for Symptomatic Simple Adrenal Cysts
A separate case report described complete and lasting cyst resolution after sclerotherapy in a patient whose symptoms initially recurred but were confirmed on repeat MRI to be unrelated to the cyst, which remained resolved.15JCEM Case Reports. Percutaneous Aspiration and Sclerotherapy as Primary Management for a Symptomatic Benign Adrenal Cyst Sclerotherapy is best suited for cysts that are clearly simple on imaging and do not raise any suspicion for malignancy, because the procedure does not yield a tissue sample for pathology. If there is any doubt about the nature of the cyst, surgery remains the better choice.
The Special Case of Parasitic Cysts
Hydatid cysts caused by the Echinococcus tapeworm account for a small fraction of adrenal cysts, but they behave very differently from other types. The adrenal gland is an unusual location for hydatid disease; the parasite overwhelmingly targets the liver and lungs.16PubMed Central. Incidentally detected hydatid cyst of the adrenal gland: a case report When it does reach the adrenal gland, the cyst is often found incidentally, just like other adrenal cysts. But the potential complications are more alarming. Rupture of a hydatid cyst can trigger anaphylaxis, a life-threatening allergic reaction caused by leakage of parasitic material. The cyst can also press on the renal artery and cause hypertension, or compress the adrenal medulla and mimic a pheochromocytoma, producing headaches, palpitations, and blood pressure spikes. In rare instances, the cyst can form a connection (fistula) to adjacent bowel.17PubMed Central. Primary hydatid cyst of adrenal gland: Case report
If you live in or have traveled to a region where hydatid disease is common, doctors may order blood tests for Echinococcus antibodies when they find a cyst with certain imaging characteristics, such as a daughter-cyst pattern or calcified wall typical of hydatid disease. Treatment usually involves surgical removal, often with pre- and post-operative anti-parasitic medication to reduce the risk of spillage and recurrence.
Why Adrenal Cysts Are Sometimes Mistaken for Something Else
One underappreciated wrinkle with adrenal cysts is that they can be misidentified on imaging as belonging to a nearby organ entirely. The adrenal glands sit just above the kidneys and close to the pancreas, spleen, and liver. A large cyst at the top of the adrenal gland can look like it originates from the upper pole of the kidney, leading to a misdiagnosis of a renal cyst or even a cystic kidney cancer.18PubMed Central. Adrenal cyst misdiagnosed with cystic renal cell carcinoma: A case report On the left side, a large adrenal cyst can be mistaken for a pancreatic cystic tumor, which carries a very different set of implications and management guidelines. In one published case, an adrenal cyst was followed for an extended period as a suspected pancreatic tail tumor before its true origin was identified.19PubMed Central. Large adrenal cyst masquerading as a pancreatic cystic tumor: a rare diagnosis based on endoscopic ultrasound
The practical consequence is that misidentification can lead to unnecessary worry, wrong treatment plans, or delayed recognition of what is actually a benign adrenal cyst. If you have been told you have a suspicious cyst near your kidney or pancreas and something does not quite fit the clinical picture, the possibility that the cyst actually arises from the adrenal gland is worth discussing with your medical team.
Adrenal Cysts in Children and During Pregnancy
Adrenal cysts in newborns and children deserve special mention because the diagnostic considerations differ. In neonates, an adrenal cyst may present as a palpable abdominal mass, sometimes accompanied by anemia or persistent jaundice. Adrenal hemorrhage is relatively common in newborns, particularly after difficult deliveries, and can leave behind a pseudocyst. The key concern in pediatric patients is distinguishing a benign hemorrhagic cyst from a cystic tumor. Neuroblastoma, the most common solid tumor of infancy outside the brain, can present as a cystic adrenal mass, and other tumors like ganglioneuroma or pheochromocytoma may also have cystic components. Ultrasound and sometimes MRI are preferred over CT in young children to avoid radiation exposure, and the threshold for further investigation tends to be lower than in adults because of the tumor risk.
During pregnancy, an adrenal cyst presents a different kind of dilemma. A growing cyst can be discovered during routine prenatal imaging and may mimic an ovarian or other pelvic mass. Ultrasound and MRI, both safe for the fetus, can help pin down the origin. In most cases, conservative management through the pregnancy is preferred, with surgery deferred until after delivery unless the cyst causes acute symptoms or complications.20PubMed. Benign adrenal cyst presenting in a pregnant patient
How Pseudocysts Form
The origin of adrenal pseudocysts has been debated, but the leading explanation is that they are a late consequence of bleeding within the adrenal gland. Unlike true cysts that have a specialized cellular lining, pseudocysts are essentially walled-off collections of old blood products. Immunohistochemical studies of removed pseudocysts have found evidence of vascular disruption and a reparative process called papillary endothelial hyperplasia, supporting the idea that these lesions begin as hemorrhages that the body walls off over time.21PubMed. Adrenal Pseudocysts: Evidence of Their Posthemorrhagic Nature This hemorrhagic origin also explains why pseudocysts sometimes contain internal debris or higher-density material on imaging, features that can complicate the task of distinguishing them from cystic tumors. The adrenal gland has a rich blood supply and is susceptible to hemorrhage from trauma, stress, anticoagulant use, and other causes, which probably accounts for why pseudocysts are the second most common type of adrenal cyst despite having no true epithelial or endothelial lining.