Pituitary spot found by chance: follow-up MRI and tests
A pituitary spot, or pituitary incidentaloma, is a finding in the small gland under the brain seen on a brain MRI or CT done for another reason. The most common are adenomas (benign growths), followed by fluid-filled cysts (Rathke cleft cysts) and an empty sella. (Hwang 2025) This page covers which tests and scans guidance lists and how often, not surgery, medicine or treatment.
The main guidance
- Endocrine Society 2011: first tests and follow-up for a pituitary spot found by chance. (Endocrine Society 2011)
- Pituitary Society 2025: an international consensus on when hormone tests, a dedicated pituitary MRI and eye field checks are needed for large spots, small spots, cysts and an empty sella, with special notes for people with multiple endocrine neoplasia type 1, children, older people and pregnancy. (Pituitary Society 2025) Its full text is behind a paywall; its follow-up intervals below come from an open-access summary. (Hwang 2025)
- ACR 2018 white paper (American College of Radiology): an algorithm for pituitary findings on CT, MRI and PET that ends either with stopping follow-up for a spot judged harmless or with a management step. (ACR 2018)
MedlinePlus notes that small spots found during an MRI for other symptoms can often be followed with repeat MRI if they are not causing hormone problems, and that many do not grow. (MedlinePlus)
Size sorts the plan
A microadenoma is under 1 cm across; a macroadenoma is 1 cm or more. (Endocrine Society 2011) In pooled studies, 24% of large spots grew over time and 8% of people with large spots developed eye field problems, while 10.6% of small spots grew over 2.3 to 7 years. (Endocrine Society 2011)
First checks
- Blood tests for too much hormone: the Endocrine Society lists them for everyone with a pituitary spot, including people with no symptoms. (Endocrine Society 2011) The Pituitary Society summary lists prolactin, IGF-1, cortisol, thyroid tests and sex hormones when indicated. (Hwang 2025)
- Blood tests for too little hormone: the Endocrine Society lists them for everyone, with or without symptoms. (Endocrine Society 2011) Giraldi 2023 lists them for spots larger than 6 mm. (Giraldi 2023)
- Dedicated MRI: if the spot was first seen on CT, an MRI to show it better. (Endocrine Society 2011)
- Eye field check (a test of side vision): when the spot touches the optic nerves or the crossing point of the nerves (the chiasm), or when there are eye symptoms. (Endocrine Society 2011)(Hwang 2025)
Repeat MRI and tests
| Check | Endocrine Society 2011 | Pituitary Society 2025 |
|---|---|---|
| MRI, small spot | At 1 year, then every 1 to 2 years for 3 years, then less often if unchanged | Every 2 to 3 years, longer if no growth |
| MRI, large spot | At 6 months, then yearly for 3 years, then less often if unchanged | Every 6 to 12 months at first, then every 1 to 2 years if stable |
| Hormone blood tests | Large spot: at 6 months, then yearly. Small stable spot: not needed | Every 1 to 2 years |
| Eye field check | If the spot grows to touch or press on the optic nerves or chiasm; not needed if far from the chiasm, with no new symptoms and close MRI follow-up | At 1 to 2 years for large spots; at 6 to 12 months for large spots under yearly MRI; closer checks for spots within 5 mm of the chiasm |
Sources for the table: the Endocrine Society column from recommendations 2.1.1 to 2.1.3, the Pituitary Society column from the open-access summary. (Endocrine Society 2011)(Hwang 2025)
What changes the plan
- Growth on a later MRI means more frequent or more detailed checks. (Endocrine Society 2011)
- New symptoms such as vision changes, other nerve problems or signs of hormone change mean an earlier check. (Endocrine Society 2011)(Hwang 2025)
- A spot close to the optic chiasm, especially within 5 mm, needs closer follow-up. (Hwang 2025)
- A spot that makes too much hormone is managed under the guidance for that hormone condition. (Hwang 2025)(Giraldi 2023)
- Multiple endocrine neoplasia type 1 is one of the special situations the Pituitary Society addresses. (Pituitary Society 2025) For screening in that condition, see screenings for people with multiple endocrine neoplasia.
MedlinePlus, when to contact a medical professional: "Contact your provider if you develop any symptoms of a pituitary tumor." (MedlinePlus) MedlinePlus lists pressure symptoms from a larger tumor such as changes in vision (double vision, loss of side vision, drooping eyelids or changes in colour vision), headache, lack of energy, clear salty fluid from the nose, nausea and vomiting, and problems with smell. (MedlinePlus)
Routine age-based screening
A pituitary spot found by chance does not replace the routine screenings for your age. For other findings on a scan, see adrenal mass found by chance, lung nodule found by chance and kidney cyst found by chance.
Where they differ:
- How often to scan a small spot. The Endocrine Society lists MRI at 1 year, then every 1 to 2 years for 3 years; the Pituitary Society summary lists every 2 to 3 years. (Endocrine Society 2011)(Hwang 2025)
- Hormone tests over time. The Endocrine Society says a small spot that stays the same does not need repeat tests for low hormone levels; the Pituitary Society summary lists hormone tests every 1 to 2 years. (Endocrine Society 2011)(Hwang 2025)
- Who gets tests for low hormone levels at the start. The Endocrine Society lists them for everyone; Giraldi 2023 lists them for spots larger than 6 mm. (Endocrine Society 2011)(Giraldi 2023)
Your doctor decides what your result means for you.
Questions people ask
How common is a pituitary spot found by chance?
Common. Across autopsy studies about 1 in 10 people had a small pituitary adenoma, and brain MRI done for other reasons shows a small spot in 10 to 38% of adults. (Endocrine Society 2011)
What is the difference between a microadenoma and a macroadenoma?
Size. A micro spot is under 1 cm across and a macro spot is 1 cm or more. Guidance follows the larger ones more often. (Endocrine Society 2011)
Do small pituitary spots grow?
Rarely. In the studies the Endocrine Society pooled, 1.7% of small spots grew each year, compared with 8.2% of all spots, and none of the people with small spots developed new eye field problems. (Endocrine Society 2011)
Why do I need blood tests if I feel well?
Some spots make too much of a hormone or press on the gland so it makes too little, sometimes before symptoms show. The Endocrine Society and the Pituitary Society both list hormone blood tests at the first visit, including for people with no symptoms. (Endocrine Society 2011) (Hwang 2025)
Will I need MRI scans forever?
Not usually as often. If the spot does not change, guidance spaces the scans out over time, and the ACR algorithm ends with stopping follow-up once a spot is judged slow and harmless. (Endocrine Society 2011) (Hwang 2025) (ACR 2018)
Related
- Thyroid nodule found by chance on CT or MRI
- Bone spot found by chance: follow-up scans
- Adrenal mass found by chance: follow-up tests
- Screenings for people with multiple endocrine neoplasia
- Lung nodule found by chance: follow-up scans
- Kidney cyst found by chance: Bosniak follow-up
- Spleen lesion found by chance: follow-up scans
- After an abnormal screening result
- Screenings by age and gender