Pineal cyst found by chance on a brain MRI

What the report means

What it is. The pineal gland is a small gland in the centre of the brain. A pineal cyst is a benign, fluid-filled sac inside it. Most cause no symptoms and are found by chance on a scan. (Majovsky 2018)(Al Mutawa 2025)
Found by MRI. MRI uses magnets, radio waves and a computer to make detailed pictures of soft tissue. (MedlinePlus) Pineal cysts are best seen on MRI, and they are found more often as more people have brain scans with sharper images. (Al Mutawa 2025)(Gokce 2018)
"Typical" cyst. Radiologists call a cyst typical when it is a single round or oval sac with a smooth edge, an even inside and a thin rim no thicker than 2 mm. (Gokce 2018)(Majovsky 2018) In one study of 56 cysts, 62.5% were typical. (Gokce 2018)
Common findings on brain scans. Unexpected findings on brain MRI are common, and they become more common with age. (Morris 2009)

How common small cysts are in adults

Depends on how small you count. Counting only cysts of 5 mm or more, studies find them on 0.99% to 4.3% of brain MRIs. With looser criteria the figure is 23% to 41%. (Hvingelby 2025) At autopsy, pineal cysts are found in up to 40% of people. (Al Mutawa 2025)
In healthy adults. Among 994 healthy volunteers with an average age of 47, 37.5% had a pineal cyst. Most were a small cyst in a mainly solid gland. Cysts 10 mm or larger were seen in 5.1%. (Warsza 2023)
In hospital scans. In 9,546 brain MRIs in one hospital, a pineal cyst was reported in 0.58%. (Gokce 2018) In 42,099 brain MRIs at a UK centre, 281 cysts were found, with a median size of 10 mm. (Nevins 2016)
More often in women. Pineal cysts were more frequent in women than in men in healthy volunteers. (Warsza 2023) In hospital series, 63% to 79% of people with a cyst were women. (Nevins 2016)(Gokce 2018)

Do they change over time?

Mostly stable. In 409 people followed for a median of 10.7 years, 5.1% of cysts grew by 2 mm or more and 13.9% shrank. Growth was mainly in people under 50, and no one needed an operation. (Hasegawa 2023)
Other series agree. In 133 people, 87.2% of cysts were stable, 5.3% grew and 7.5% shrank. (Majovsky 2018) In 130 people followed for more than a year, 90.7% were stable. (Hvingelby 2025) Across 18 months in a UK series, the average change in size was 0.04 mm. (Storey 2020)
Age, not size, linked to growth. People whose cysts grew were younger, and the first size did not predict whether a cyst would grow or shrink. (Majovsky 2018)(Hasegawa 2023)

The size and look that lead to a follow-up scan

A typical cyst with no symptoms. Several centres found that routine follow-up of pineal cysts is not needed when the cyst looks typical and causes no related symptoms. (Storey 2020)(Tanaka 2021)
One check scan. A UK centre recommends a single follow-up MRI at 12 months to confirm the diagnosis, then discharge if the cyst is stable. (Nevins 2016)
An unusual look. A wall thicker than 2 mm, several compartments, a lobed edge or uneven enhancement makes a cyst "atypical". Rapid growth or these features can make it harder to tell a cyst from a tumour, which is when more checks are considered. (Gokce 2018)(Majovsky 2018)
Size and the fluid channel. A large cyst that presses on the channel that drains brain fluid (the aqueduct) can cause headache, nausea and vomiting. (Al Mutawa 2025) In a UK series, the only people who needed treatment had cysts over 20 mm with fluid build-up already present. (Storey 2020) In children, many centres have used 10 mm as a point for a follow-up MRI. (Jussila 2017)
Radiology guidance. In 2026 the American College of Radiology Incidental Findings Committee published consensus recommendations on managing pineal cysts found by chance on CT and MRI. (ACR 2026) Ask what the radiologist's report suggests for your scan.
Worry is real. See after an abnormal screening result.

How it ties to your age-based checks

A pineal cyst found by chance is a good moment to make sure your routine checks are up to date:

Other brain scan findings have their own pages: small meningioma found by chance, white matter changes on a brain MRI and small brain aneurysm found by chance.

Who it applies to

Adults told that a brain MRI or CT done for another reason shows a pineal cyst, with no symptoms from it. Children, people with fluid build-up in the brain (hydrocephalus) and people with eye movement problems linked to the cyst are outside this page.

The NHS advises an urgent GP appointment or NHS 111 for a headache with vision or eye problems, a headache made worse by coughing, sneezing or bending down, or a headache with vomiting. Call 999 (911 in the US) for a headache with a seizure, numbness or weakness, sudden extreme pain, trouble speaking, balancing, walking or remembering, drowsiness or confusion, or loss of vision. (NHS)

Routine age-based screening

A finding on a brain scan does not replace the routine screenings for your age. See screenings by age and gender.

Where they differ:

No scan or one scan. Storey and Tanaka found routine follow-up is not needed for a typical cyst without symptoms. (Storey 2020)(Tanaka 2021) Nevins suggests one MRI at 12 months, then discharge if stable. (Nevins 2016) At a Swedish centre all people with a cyst of 5 mm or more were advised a follow-up MRI after 1 year. (Hvingelby 2025)
How common. Figures range from 0.58% of hospital brain MRIs to 37.5% of healthy volunteers, depending on the scan and how small a cyst is counted. (Gokce 2018)(Warsza 2023)
Who grows. One study found growth mainly under age 50 (Hasegawa 2023), while another saw growth in younger people as normal and size as no guide to change. (Majovsky 2018)

Your doctor decides what your result means for you.

Questions people ask

How common is a pineal cyst?

Very common. With a 5 mm cut-off, studies find them on about 1% to 4% of brain MRIs, and with looser criteria on 23% to 41%. In 994 healthy volunteers, 37.5% had a pineal cyst of some size, and 5.1% had one 10 mm or larger. (Hvingelby 2025) (Warsza 2023)

Is a pineal cyst a tumour?

No. It is a fluid-filled sac in the pineal gland, a small gland deep in the middle of the brain. Most cause no symptoms and are found by chance. (Al Mutawa 2025) (Majovsky 2018)

Will it grow?

Most stay the same size. In 409 people followed for a median of 10.7 years, 5.1% of cysts grew, mainly in people under 50, and 13.9% shrank. None needed an operation. (Hasegawa 2023)

Do I need a repeat MRI?

Several UK and US centres found that a typical cyst without symptoms needs no routine follow-up. One UK centre suggests a single MRI at 12 months, then discharge if it is stable. Your doctor decides. (Storey 2020) (Tanaka 2021) (Nevins 2016)

Can a pineal cyst cause headaches?

Headache is the most common reason people have the scan, but in a 2025 study cyst size was not linked to headache. A large cyst that presses on the brain fluid channel can cause headache, nausea and vomiting. (Hvingelby 2025) (Al Mutawa 2025)