What Is a Brenner Tumor? Types, Symptoms, Causes, Diagnosis, and Treatment
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer
A Brenner tumor is a rare growth on the ovary [1] [3]. Most Brenner tumors are benign, are found accidentally during imaging tests and are treated successfully with surgery [1]. Although the word tumor sounds alarming, the most common outcome is a small, noncancerous growth that is resolved by removing it, so the overall outlook is usually reassuring.
Key takeaways
A Brenner tumor is a rare ovarian tumor that most commonly affects women in their 50s to 70s [1].
Most cases cause no symptoms and are found by chance during imaging tests ordered for other reasons [1] [3].
The three types — benign, borderline, and malignant — are distinguished by how the cells look under a microscope [1].
Benign tumors are the most common and usually measure under 2 centimeters [1].
Surgery is the main treatment for every type [1], and removal is usually the only treatment needed.
Malignant Brenner tumors account for fewer than 5% of cases [1] and may require chemotherapy or radiation [1].
What the research says
Most Brenner tumors are found by chance. In a 10-year single-institution review of nine benign Brenner tumors, the average age at diagnosis was 58 years and seven of the nine were discovered incidentally; tumors ranged from 0.2 to 7.5 cm, and Walthard rests were found alongside six of the nine (Alloush et al., Medical Sciences, 2023) [2].
Small, symptom-free tumors are the typical picture, but a second ovarian growth is common. A radiology review found that most Brenner tumors are under 2 cm and detected incidentally in asymptomatic women, with a second ovarian neoplasm reported in up to 30% of patients (Costeira et al., British Journal of Radiology, 2022) [3].
Malignant Brenner tumors are rare but can come back. A critical reappraisal reported that more than half are diagnosed at stage I, with recurrence in 47.7% and mortality of at least 20%, and that treatment is not standardized (surgery with or without chemotherapy) (Turashvili and Hanley, International Journal of Gynecological Pathology, 2025) [5].
What Is a Brenner Tumor?
A Brenner tumor is a rare ovarian tumor. Most cases are noncancerous, or benign [1]. These tumors most commonly affect women in their 50s to 70s, although they can develop at any age [1].
Because Brenner tumors are rare, researchers are still learning about the best ways to diagnose and treat them [1].
Brenner Tumor Types
The World Health Organization (WHO) classifies Brenner tumors into three types based on how the cells appear under a microscope [1].
Type | Cancer status | Typical size | How common |
Benign | Noncancerous | Usually less than 2 cm | The most common Brenner tumor |
Borderline | Features of both benign and malignant; has the potential to turn into cancer | About 12 cm on average | Less common |
Malignant | Cancerous | Typically around 10 cm | Very rare — fewer than 5% of all cases |
The benign type is by far the most common. These tumors are usually small, typically measuring under 2 centimeters [1]. The borderline type has features of both benign and malignant tumors and carries the potential to become cancer [1]. The malignant type is cancerous and accounts for fewer than 5% of all Brenner tumor cases [1].
Brenner Tumor Symptoms
Most Brenner tumors do not cause symptoms. Healthcare providers typically find them by chance when a patient undergoes imaging tests for other reasons [1] [3].
When symptoms do occur, they can include [1]:
A buildup of fluid in the abdomen, known as ascites
A mass in the pelvis
Fullness, pain, or pressure in the abdomen
These symptoms can have many other causes [1]. If you experience any of them, it is important to see a healthcare provider so they can identify the underlying problem.
Brenner Tumor Causes
Researchers do not know the exact cause of Brenner tumors. In general, tumors form when cells grow uncontrollably [1].
With Brenner tumors specifically, researchers think this uncontrolled growth happens in small groups of cells located near the fallopian tubes and ovaries. These cell clusters are called Walthard cell nests [1].
Loss of function of CDKN2A, a tumor suppressor gene, may also cause benign Brenner tumors to progress into borderline tumors [1]. Tumor suppressor genes normally help keep cell growth in check, so when they stop working, growth can accelerate.
Factor | What is known |
Exact cause | Unknown; tumors form when cells grow uncontrollably |
Cell origin | Small groups of cells near the fallopian tubes and ovaries (Walthard cell nests) |
Genetic link | Loss of function of the CDKN2A tumor suppressor gene may cause benign tumors to become borderline |
Typical age | Most common in women in their 50s to 70s, but can develop at any age |
How Is a Brenner Tumor Diagnosed?
In most cases, a Brenner tumor is discovered by chance during imaging tests of the pelvis performed for other reasons [1].
If symptoms are present, a healthcare provider may recommend one or more of the following imaging tests [1]:
Test | What it does |
Ultrasound | Uses sound waves to create pictures of the ovaries and pelvis |
CT scan | Uses X-rays to create detailed cross-sectional images |
MRI | Uses magnetic fields to produce detailed soft-tissue images |
Imaging alone cannot determine the tumor type. To make a definitive diagnosis, the tumor must be surgically removed. The surgeon then sends tissue samples to a laboratory, where a pathologist examines the cells under a microscope to determine whether the tumor is benign, borderline, or malignant [1].
Brenner Tumor Treatment
Surgery is the main form of treatment for all types of Brenner tumors [1]. The surgeon removes all or part of the tumor [1].
Surgical removal usually accomplishes two goals at once. It resolves any symptoms caused by the tumor, and it provides the tissue samples needed to determine the tumor type [1].
If the tumor is malignant, additional treatments may be necessary. These may include chemotherapy or radiation therapy [1]. Because malignant Brenner tumors are so rare, healthcare providers do not have a standardized treatment plan for them [1] [5]. Your healthcare team will walk you through your options.
Treatment Overview by Tumor Type
Tumor type | Primary treatment | Additional treatment if needed |
Benign | Surgery to remove all or part of the tumor | Usually none; removal typically resolves symptoms |
Borderline | Surgery | Follow-up determined by pathology results |
Malignant | Surgery | Chemotherapy, radiation, or other options discussed with your healthcare team |
Living With a Brenner Tumor Diagnosis
A tumor diagnosis — especially a rare one — can trigger a flood of emotions. The volume of new information can feel overwhelming.
The reassuring news is that Brenner tumors are often benign [1]. Your healthcare provider will go over the next steps with you. Lean on them, and on loved ones, for support as you work through the diagnosis and treatment plan.
Conclusion
A Brenner tumor is a rare ovarian growth that sounds more alarming than it usually is. Most cases are benign, small, and symptom-free, discovered only by accident during imaging for other reasons. When treatment is needed, surgery removes the tumor, resolves symptoms, and provides the definitive diagnosis. Even in the rare malignant cases, a full healthcare team is available to build an individualized plan.
If you or a loved one has been diagnosed with a Brenner tumor, talk with your healthcare provider about the pathology results, the recommended surgical approach, and what follow-up looks like for your specific case.
Frequently Asked Questions
What is a Brenner tumor?
A Brenner tumor is a rare ovarian tumor. Most cases are benign (noncancerous), and they most commonly affect women in their 50s to 70s, although they can develop at any age.
Is a Brenner tumor cancer?
Usually not. Most Brenner tumors are benign. A small share are borderline, meaning they have features of both benign and malignant tumors. Malignant Brenner tumors are cancerous but account for fewer than 5% of all cases.
How common are Brenner tumors?
Brenner tumors are rare. Because they are so uncommon, researchers are still learning about the best ways to diagnose and treat them.
What causes a Brenner tumor?
The exact cause is unknown. Researchers believe these tumors develop in small groups of cells near the fallopian tubes and ovaries called Walthard cell nests, where cells begin to grow uncontrollably.
Can a genetic change cause a Brenner tumor to worsen?
Loss of function of the CDKN2A tumor suppressor gene may cause benign Brenner tumors to turn into borderline tumors.
What are the symptoms of a Brenner tumor?
Most Brenner tumors cause no symptoms. Possible symptoms include fluid buildup in the abdomen (ascites), a pelvic mass, and fullness, pain, or pressure in the abdomen.
Why are Brenner tumors usually found by accident?
Because they typically cause no symptoms, healthcare providers most often discover them by chance during imaging tests of the pelvis performed for other reasons.
Who is most likely to develop a Brenner tumor?
Women in their 50s to 70s are most commonly affected, although these tumors can develop at any age.
What are the three types of Brenner tumors?
The World Health Organization classifies them as benign (noncancerous), borderline (features of both benign and malignant), and malignant (cancerous), based on how the cells look under a microscope.
How big do Brenner tumors get?
Benign tumors are usually less than 2 centimeters. Borderline tumors average about 12 centimeters, and malignant tumors are typically around 10 centimeters.
How is a Brenner tumor diagnosed?
Imaging tests such as ultrasound, CT scans, or MRI can detect the tumor, but a definitive diagnosis requires surgical removal. A pathologist examines the tissue under a microscope to determine the tumor type.
What tests detect a Brenner tumor?
Ultrasound, CT scans, and MRI of the pelvis are the imaging tests most commonly used to identify the tumor.
Is surgery always needed?
Surgery is the main treatment for all types of Brenner tumors, because removal resolves symptoms and is the only way to determine the tumor type.
What happens if a Brenner tumor is malignant?
Additional treatments such as chemotherapy or radiation may be needed. Because malignant cases are so rare, there is no standardized treatment plan, and your healthcare team will discuss your options individually.
Does surgery usually resolve symptoms?
Yes. Removing all or part of the tumor usually resolves any symptoms it was causing.
Can a Brenner tumor come back after surgery?
Your healthcare provider will discuss follow-up based on your pathology results. Follow-up plans depend on whether the tumor was benign, borderline, or malignant.
Is a Brenner tumor related to ovarian cancer?
A malignant Brenner tumor is a rare form of ovarian cancer. However, the overwhelming majority of Brenner tumors are benign and not cancer.
What should I do if I was told I have a Brenner tumor?
Stay calm — most are benign. Meet with your healthcare provider to review your imaging results, discuss the recommended surgical approach, and understand what follow-up your specific case requires.
Related Reading
References
Cleveland Clinic. Brenner Tumor. Cleveland Clinic Health Library. Medically reviewed; last updated September 17, 2025. Accessed October 15, 2026. https://my.clevelandclinic.org/health/diseases/brenner-tumor
Alloush F, Bahmad HF, Lutz B, et al. Brenner tumor of the ovary: a 10-year single institution experience and comprehensive review of the literature. Med Sci (Basel). 2023;11(1):18. PMID 36810485. https://doi.org/10.3390/medsci11010018
Costeira FS, Félix A, Cunha TM. Brenner tumors. Br J Radiol. 2022;95(1130):20210687. PMID 34928171. https://doi.org/10.1259/bjr.20210687
Lou Z, Mei L, Wan Z, et al. A report of twenty cases of ovarian Brenner tumor and literature review: a case series study. BMC Womens Health. 2024;24(1):471. PMID 39192213. https://doi.org/10.1186/s12905-024-03316-4
Turashvili G, Hanley K. Malignant Brenner tumor of the ovary: a critical reappraisal. Int J Gynecol Pathol. 2025;44(2):182-192. PMID 39778112. https://doi.org/10.1097/PGP.0000000000001060
Medical disclaimer
This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified healthcare provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay seeking it because of something you have read on this website.
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