Incidental Findings on MRI: What They Mean and When They Matter

An incidental MRI finding is an abnormality discovered unexpectedly that may be unrelated to the symptoms being investigated. Many incidental findings—such as age-related disc changes, degenerative meniscus tears and some tendon abnormalities—require no specific treatment. Others may need monitoring, additional imaging or timely medical assessment, depending on their appearance and the patient’s circumstances.

What Is an Incidental Finding?

An incidental finding is something seen on a scan that was not the main reason the examination was performed.

For example, a patient may undergo a lumbar spine MRI for right-leg pain. The MRI may show:

• A disc abnormality that corresponds with the right-leg symptoms
• Degenerative changes that are probably unrelated
• A cyst or other unexpected finding outside the spine

The first finding may help explain the symptoms. The other findings may be incidental.

An incidental finding is not necessarily insignificant. “Incidental” describes how it was discovered—not whether it is harmless, serious or in need of follow-up.

Why Are Incidental Findings Common on MRI?

MRI produces highly detailed images and can detect structural differences that may not cause symptoms.

Incidental findings are particularly common because:

• Human anatomy varies naturally.
• Tissues change with age.
• Previous injuries can remain visible after symptoms resolve.
• Some abnormalities develop without causing pain.
• MRI can detect very small structural changes.
• The scanned area may include organs or tissues unrelated to the original problem.

The probability of finding at least one abnormality generally increases with age and with the amount of anatomy scanned.

This creates an important distinction:

An MRI can identify an abnormal structure without proving that the structure is the source of pain.

Does “Incidental” Mean the Finding Can Be Ignored?

No. Incidental findings can be divided broadly into three groups.

Category	What it generally means	Possible response
Common and probably unrelated	Frequently found in people without symptoms	No specific treatment may be needed
Potentially relevant	Could contribute to symptoms but requires clinical correlation	Compare with symptoms and examination
Unexpected and potentially important	May represent a condition requiring clarification or follow-up	Further assessment, monitoring or referral may be appropriate

The radiologist may recommend comparison with previous imaging, clinical correlation, targeted imaging or another form of follow-up.

These recommendations should be interpreted by the referring healthcare professional rather than followed mechanically without considering the patient’s circumstances.

Common Incidental Findings on Spine MRI

Disc degeneration

Disc degeneration may include:

• Reduced disc hydration
• Loss of disc height
• Disc bulging
• Small disc protrusions
• Annular fissures
• Osteophytes

Such changes become increasingly common with age and can appear in people without back or neck pain.

They may still be clinically relevant when they correspond with:

• The location of symptoms
• A compatible nerve distribution
• Weakness or sensory change
• Restricted function
• Other supportive examination findings

Disc bulges

A disc bulge is a broad extension of disc tissue beyond its usual boundary. It may be incidental when it does not significantly affect a nerve or correspond with symptoms.

A bulge on the left side is less likely to explain symptoms confined to the right leg, although each case requires individual interpretation.

Spinal stenosis

Spinal stenosis means narrowing of the spinal canal or a nerve opening. Some people have radiological narrowing without substantial symptoms.

The finding becomes more significant when it corresponds with features such as:

• Leg symptoms brought on by standing or walking
• Numbness or weakness
• Altered reflexes or sensation
• Reduced walking tolerance
• Signs of spinal cord dysfunction in the neck

Vertebral haemangioma

A vertebral haemangioma is a usually benign collection of blood vessels within a vertebra. Typical haemangiomas are common incidental findings and frequently require no treatment.

Atypical appearances may require further characterisation, particularly if the radiologist cannot confidently identify the lesion as benign.

Perineural or Tarlov cyst

A Tarlov cyst is a fluid-containing structure around a nerve root, most often in the sacral spine. Many are incidental.

Its relevance depends on size, location and whether there is a plausible relationship with neurological symptoms.

Common Incidental Findings on Knee MRI

Degenerative meniscus tears

Meniscus abnormalities become more common with age and frequently coexist with knee osteoarthritis. Some people with MRI-confirmed tears have no knee pain.

A degenerative meniscus tear is more likely to be incidental when:

• There was no relevant injury
• Symptoms do not correspond with the affected area
• There is no mechanical restriction
• Knee arthritis provides a more plausible explanation
• Examination does not support meniscal involvement

The word “tear” does not by itself determine whether surgery is necessary.

Cartilage wear

MRI may identify cartilage thinning, fissuring or full-thickness loss.

Cartilage changes can be clinically important, but their severity does not always correspond with pain severity. Treatment is usually guided by symptoms and function rather than the scan alone.

Small joint effusion

An effusion is excess fluid within a joint. A small amount may be nonspecific and does not identify its cause.

Larger or symptomatic effusions may occur with:

• Injury
• Osteoarthritis
• Inflammatory arthritis
• Crystal arthritis
• Infection

The clinical context matters.

Baker’s cyst

A Baker’s cyst is a fluid-filled structure behind the knee, usually associated with fluid from within the joint.

Many Baker’s cysts are incidental. Treatment is generally directed at the underlying knee condition rather than the cyst itself unless it is causing specific problems.

Common Incidental Findings on Shoulder MRI

Rotator cuff tendinopathy

Tendinopathy refers to structural changes within a tendon. Such changes may appear even when the shoulder is not painful.

The finding is more likely to be relevant when pain and weakness correspond with the affected tendon.

Partial or full-thickness rotator cuff tears

Rotator cuff tears become more common with age and may be found in people without symptoms.

Clinical importance depends on:

• Whether the tear followed an injury
• Tear size and location
• Weakness
• Functional loss
• Tendon retraction
• Muscle atrophy or fatty change
• The patient’s activity requirements

An incidental rotator cuff tear does not automatically require surgery.

Labral abnormalities

The shoulder labrum may show degenerative changes or tears, particularly with age or previous activity.

Labral findings are more persuasive when they match the injury mechanism, symptoms and examination. They may otherwise be incidental.

Acromioclavicular joint degeneration

Degeneration of the joint at the top of the shoulder is common. It may be incidental unless there is localised tenderness or pain corresponding with that joint.

Common Incidental Findings on Hip and Pelvic MRI

Labral tears

Hip labral abnormalities can appear in people without hip pain. Their presence does not prove that they are responsible for symptoms.

Relevant factors include:

• Groin pain
• Pain during specific hip movements
• Mechanical symptoms
• Examination findings
• Associated bone shape and cartilage damage

Gluteal tendon abnormalities

Gluteal tendinopathy or partial tears may be found incidentally, particularly in older adults. These findings become more meaningful when they correspond with outer-hip pain and relevant examination findings.

Simple cysts or benign-appearing lesions

MRI of the hip or spine may include parts of the pelvis or abdomen. The radiologist may identify cysts or other findings in nearby organs.

Some require no action. Others may need targeted assessment based on the patient’s age, sex, symptoms and the lesion’s imaging appearance.

Unexpected Findings Outside the Musculoskeletal System

An MRI may include anatomy beyond the joint or spine being investigated. Possible unexpected findings include abnormalities involving:

• Kidneys
• Liver
• Ovaries or uterus
• Prostate
• Blood vessels
• Lymph nodes
• Soft tissues
• Bone marrow

A musculoskeletal MRI may not be designed to characterise these structures fully. If an unexpected finding is identified, the radiologist may recommend:

• Review of earlier scans
• Ultrasound
• CT
• A dedicated MRI
• Laboratory testing
• Assessment by an appropriate healthcare professional
• Interval imaging to confirm stability

A recommendation for further investigation does not necessarily mean the finding is cancerous or dangerous. It usually means the available scan cannot fully characterise it.

How Doctors Decide Whether a Finding Matters

A finding is more likely to be clinically relevant when several factors align.

1. The anatomical location matches

The abnormality should be capable of affecting the region where symptoms occur.

For example, a nerve finding at one spinal level should correspond reasonably with the patient’s pain, numbness or weakness pattern.

2. The side matches

A left-sided abnormality is less convincing as the cause of symptoms occurring exclusively on the right.

There are exceptions, but an apparent mismatch should prompt careful reassessment.

3. The type of symptom matches

Different structures tend to cause different patterns.

A tendon abnormality might correspond with pain during resisted movement, while nerve compression may produce radiating pain, numbness or weakness.

4. The timing makes sense

A finding is more persuasive when it corresponds with the timing and mechanism of symptoms.

A longstanding degenerative change may be less likely to explain sudden pain after a new injury unless the injury has aggravated it or produced an additional problem.

5. Examination findings support it

Relevant weakness, tenderness, restricted movement or altered sensation can strengthen the relationship between an MRI finding and the symptoms.

6. Alternative explanations have been considered

Pain can arise from another joint, referred pain, nerve sensitivity, muscular loading or a condition not clearly visible on MRI.

MRI Findings That May Need More Urgent Attention

Certain unexpected findings may require timely medical review. Examples include:

• A suspicious bone or soft-tissue mass
• Spinal cord compression
• Cauda equina compression
• An acute fracture
• Possible bone or joint infection
• Severe inflammation accompanied by systemic illness
• Osteonecrosis
• A significant tendon rupture after recent trauma
• A vascular abnormality
• An unexpected finding specifically marked urgent by the radiologist

The urgency depends on both the imaging appearance and the patient’s symptoms.

What Does “Clinical Correlation Recommended” Mean?

This phrase means that the imaging finding should be compared with:

• The patient’s symptoms
• Clinical history
• Physical examination
• Laboratory results, where relevant
• Previous imaging
• Other diagnostic information

It does not necessarily mean that the finding is serious. It means that imaging alone cannot determine its clinical significance.

What Does “Follow-Up Recommended” Mean?

A radiologist may recommend follow-up when a finding:

• Cannot be fully characterised on the current scan
• Needs to be checked for stability
• Is probably benign but not completely typical
• Lies outside the intended scope of the examination
• May require a more suitable imaging technique

Follow-up could involve another imaging modality rather than a repeat of the same MRI.

The appropriate next step should be decided with a healthcare professional who understands the full clinical context.

Potential Harms of Overreacting to Incidental Findings

Treating every abnormality as a disease can lead to:

• Unnecessary anxiety
• Additional tests that do not improve health outcomes
• Treatment directed at the wrong structure
• Avoidable injections or procedures
• Unnecessary restriction of normal activity
• Increased healthcare costs
• A mistaken belief that the body is fragile or damaged

Patients should not ignore significant findings, but they also should not assume that every abnormality requires correction.

Potential Harms of Ignoring Incidental Findings

At the other extreme, dismissing every unexpected finding can delay assessment of a potentially important condition.

Follow-up is more important when:

• The radiologist explicitly recommends it
• The finding has uncertain or atypical features
• There is no previous imaging to establish stability
• Relevant symptoms or risk factors are present
• The patient has a history of cancer, infection or significant systemic illness
• The finding could affect the spinal cord, nerves, bone stability or another organ

The goal is proportionate follow-up based on actual risk.

Questions to Ask About an Incidental Finding

Patients may consider asking:

1. Was this finding related to the reason for the MRI?
2. Could it explain any of my symptoms?
3. Is it common in people without symptoms?
4. Does it require treatment?
5. Does it need another type of imaging?
6. Should it be compared with an earlier scan?
7. If observation is appropriate, how and when should it be reviewed?
8. What symptoms should prompt earlier assessment?
9. Is referral to another healthcare professional necessary?
10. Would doing nothing for now be medically reasonable?

Do Incidental Findings Need Treatment?

Many do not.

Treatment is usually considered only when a finding:

• Causes symptoms
• Creates a meaningful health risk
• Is likely to progress in a clinically important way
• Affects function
• Requires diagnostic clarification
• Represents a condition for which early treatment is beneficial

Age-related changes that do not correspond with symptoms often require no direct intervention.

Monitoring, reassurance and maintaining appropriate activity may be more suitable than treatment in some cases.

Should You Repeat the MRI?

A repeat MRI is not automatically necessary because an incidental finding was identified.

Repeat or additional imaging may be appropriate when:

• The original scan could not adequately characterise the finding
• The radiologist recommends interval assessment
• Symptoms have changed
• New clinical warning signs have developed
• Stability over time would help distinguish benign from concerning causes
• A different scan is required for treatment planning

If the existing images already answer the relevant question, repeating the MRI may add little.

When to Seek Prompt Medical Attention

Seek prompt assessment if an incidental finding is accompanied by:

• New or progressively worsening weakness
• Loss of bladder or bowel control
• Numbness around the saddle or genital region
• New difficulty walking or loss of coordination
• Fever with severe back or joint pain
• Severe pain after significant trauma
• Unexplained weight loss
• A history of cancer with new persistent pain
• A rapidly enlarging mass
• A hot, swollen joint with fever or systemic illness

These features do not confirm a serious condition, but they require timely evaluation.

Frequently Asked Questions

Is an incidental finding a misdiagnosis?

No. It is a genuine imaging observation that may not be related to the condition being investigated. Its importance still needs to be determined.

Does incidental mean harmless?

Not necessarily. Many incidental findings are harmless or clinically unimportant, but some require follow-up. “Incidental” describes the circumstances of discovery.

Can an incidental disc bulge become painful later?

It can, but a future episode of pain should still be assessed rather than automatically attributed to the old MRI finding.

Should an incidental meniscus tear be repaired?

Not automatically. Management depends on symptoms, injury history, mechanical restriction, arthritis, examination findings and individual goals.

Does an incidental rotator cuff tear need monitoring?

Some tears may be observed clinically, while others may warrant assessment based on size, weakness, age, activity requirements and whether the tear followed an injury. Routine repeat imaging is not necessary for every tear.

Why does the radiologist recommend another scan?

The current MRI may not fully characterise the finding, particularly if it lies outside the area the scan was designed to assess. Another imaging method may provide more suitable information.

Can an incidental finding explain symptoms that were previously unexplained?

Yes. A finding initially described as incidental may become clinically relevant after the history and examination are reviewed. The term is not always the final clinical conclusion.

Does every incidental lesion need a biopsy?

No. Many lesions have a typical benign imaging appearance. Biopsy is generally considered only when imaging and clinical assessment cannot adequately establish the nature of a potentially important lesion.

Medical Assessment

If an MRI contains an unexpected finding, a medical review can help distinguish a common incidental change from an abnormality that requires treatment, monitoring or further investigation.

The Pain Relief Clinic provides assessment by a licensed medical doctor, access to in-house physiotherapy and diagnostic imaging pathways where medically appropriate. When another type of medical or surgical review is indicated, onward referral may be considered.

For appointments or enquiries, call or WhatsApp +65 9068 9605.

References

1. Brinjikji W, Luetmer PH, Comstock B, et al. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR American Journal of Neuroradiology. 2015;36(4):811–816. PubMed
2. Englund M, Guermazi A, Gale D, et al. Incidental meniscal findings on knee MRI in middle-aged and elderly persons. New England Journal of Medicine. 2008;359:1108–1115. PubMed
3. Barreto RPG, Braman JP, Ludewig PM, Ribeiro LP, Camargo PR. Bilateral magnetic resonance imaging findings in individuals with unilateral shoulder pain. Journal of Shoulder and Elbow Surgery. 2019;28(9):1699–1706. PubMed
4. Gill TK, Shanahan EM, Allison D, Alcorn D, Hill CL. Prevalence of abnormalities on shoulder MRI in symptomatic and asymptomatic older adults. International Journal of Rheumatic Diseases. 2014;17(8):863–871. PubMed
5. Register B, Pennock AT, Ho CP, et al. Prevalence of abnormal hip findings in asymptomatic participants: a prospective, blinded study. American Journal of Sports Medicine. 2012;40(12):2720–2724. PubMed
6. Radiological Society of North America and American College of Radiology. How to Read Your Radiology Report. RadiologyInfo.org
7. American College of Radiology. ACR Appropriateness Criteria. American College of Radiology

Medical Disclaimer

This article is for general educational information and does not replace an individual medical assessment. The importance of an incidental MRI finding depends on its imaging characteristics, the patient’s symptoms, medical history, examination and individual risk factors. Seek prompt medical attention for progressive weakness, bladder or bowel changes, saddle numbness, fever with severe pain, significant trauma or other concerning symptoms.

Reviewed by Dr Terence Tan, Founder of The Pain Relief Clinic — 19 September 2026