Brenner Tumor of the Ovary: CT, MRI, and Ultrasound Findings of Calcified Ovarian Masses and Their Differential Diagnosis
1. Clinical Hook
A 53-year-old woman was referred to the radiology department because of
left lower abdominal pain.
Contrast-enhanced CT of the abdomen and pelvis revealed a heterogeneous,
relatively hyperattenuating mass measuring approximately 3–4 cm in the region
of the left ovary. Small foci of calcification were scattered throughout the
lesion. Importantly, there was no convincing evidence of a macroscopic fat
component.
Transvaginal ultrasound revealed an even more intriguing appearance. The
echogenic portions of the lesion produced prominent posterior acoustic
shadowing, while color Doppler imaging demonstrated little to no internal
vascularity.
This combination of findings immediately brings another familiar diagnosis
to mind for most radiologists:
Mature cystic teratoma.
However, this is not the point at which the interpretation should end.
Calcification and marked acoustic shadowing are well-recognized imaging
features of mature cystic teratoma. But when CT and MRI fail to demonstrate
definite fat, the mass is relatively solid, and the lesion demonstrates low
signal intensity on T2-weighted MRI, an entirely different pathologic
explanation must be considered.
One of the important differential diagnoses in this setting is Brenner
tumor of the ovary.
Brenner tumors are rare. Most are benign, although borderline and
malignant forms also exist. Therefore, the key to imaging diagnosis is not
simply memorizing a single characteristic finding. Rather, it is recognizing
the pattern created by:
Calcification + solid morphology + low vascularity + low T2 signal +
absence of convincing fat
—and relating that pattern to the underlying histopathologic architecture.
2. Learning Objectives
Through this case, the reader should understand the following five key
points:
- How to differentiate a
mature cystic teratoma from a Brenner tumor when evaluating a calcified
ovarian mass.
- How the fibrous stroma of
a Brenner tumor is reflected in its CT, ultrasound, and MRI appearance.
- The common pitfalls that arise
when interpreting low T2 signal intensity and DWI/ADC findings in relation
to malignant potential.
- How imaging findings and
clinical information may help distinguish benign, borderline, and
malignant Brenner tumors.
- How O-RADS MRI and
AI-based imaging analysis may be applied to the practical evaluation of
ovarian masses.
3. Anatomy Review
The ovaries are small reproductive organs located on either side of the
uterus. In imaging evaluation, however, identifying the relationship between
the ovary and the surrounding pelvic structures is often more important than
simply visualizing the ovary itself.
Particularly in the case of a small adnexal mass, determining the exact
site of origin from a single axial image can be challenging. Coronal and
sagittal reconstructions can provide a clearer understanding of the
relationship between the lesion and the uterus, bowel, urinary bladder, rectum,
and pelvic wall.
In this case, the lesion is located in the left adnexal region and is
considered to arise from the left ovary.
Figure 1. Adnexal Anatomy and Ovarian Mass Localization
Conceptual illustration demonstrating the anatomic relationship between
the left ovary, uterus, fallopian tube, and surrounding pelvic organs. When
evaluating a small adnexal mass, determining the organ of origin requires more
than simply identifying the mass itself. Continuity with the normal ovary, the
lesion's spatial relationship to the uterus, and displacement of adjacent
structures are all important clues.
4. Case Presentation
History
A 53-year-old woman presented with left lower abdominal pain. In the
available case material, pain was identified as the principal clinical symptom.
Symptoms
- Left lower abdominal pain
- Possible pelvic
discomfort
- Assessment for possible
pressure-related symptoms
- Assessment for abnormal
uterine bleeding
- Assessment for possible
hormone-related symptoms
An important clinical pitfall is to avoid automatically assuming a causal
relationship between the patient's pain and the ovarian mass.
A small ovarian lesion measuring approximately 3–4 cm may be discovered
incidentally on imaging performed for an unrelated reason rather than being the
direct cause of the patient's symptoms.
Physical Examination
The provided case material does not include detailed physical examination
findings. Therefore, no specific examination findings should be added or
assumed.
In actual clinical practice, the evaluation should include assessment for
abdominal tenderness, rebound tenderness, a palpable pelvic mass, abdominal
distension, and evidence of an acute gynecologic emergency.
Clinical Question
Is this small calcified solid mass in the left ovary a mature cystic
teratoma, or could it represent a fibrous Brenner tumor?
Laboratory Findings
The provided case material does not include specific laboratory values.
Tumor markers, including CA-125, may be used as adjunctive tools in
assessing the possibility of malignancy, but they do not replace imaging
evaluation or histopathologic diagnosis.
Recent literature has suggested that elevated CA-125 levels may be
observed more frequently in borderline or malignant Brenner tumors. However, a
single blood test cannot reliably distinguish benign from malignant disease.
5. Pathophysiology
Brenner tumor is a rare epithelial tumor of the ovary.
Histologically, its most characteristic feature is the presence of urothelial-like
or transitional-type epithelial cell nests embedded within a dense fibrous
stroma.
Its pathogenesis has not been completely elucidated. Proposed mechanisms
include a possible relationship with Walthard cell nests and theories involving
urothelial or transitional differentiation of the ovarian surface epithelium
and underlying stroma.
Contemporary pathologic research has also explored the possibility that
some Brenner tumors may progress along a spectrum from benign to borderline and
malignant forms, accompanied by distinct molecular alterations.
Connecting Imaging With Pathophysiology
Perhaps the simplest way to understand the imaging appearance of a Brenner
tumor is to remember one principle:
Fibrous stroma leaves an imaging signature.
Dense, collagen-rich stroma can contribute to low signal intensity on
T2-weighted MRI.
This creates the following conceptual relationship:
Dense fibrous stroma
→ Low T2 signal intensity
→ Predominantly solid morphology
→ Relatively low vascularity
→ Calcification in some lesions
However, this relationship should not be interpreted as a diagnostic
equation.
Low T2 signal ≠ Brenner tumor.
Other fibrous ovarian tumors, including ovarian fibroma and thecoma, may
also demonstrate low T2 signal intensity.
Molecular Biology
Recent studies have reported molecular alterations in Brenner tumors,
particularly in borderline and malignant forms, including:
- CDKN2A/CDKN2B loss
- FGFR3 pathway alterations
- MDM2 amplification
- KRAS alterations
- PIK3CA alterations
These findings extend beyond conventional histopathologic classification
and raise the possibility of future molecularly guided therapeutic strategies.
Figure 2. Brenner Tumor: Pathology-to-Imaging Correlation
Conceptual illustration linking the urothelial-like epithelial nests and
dense fibrous stroma of a Brenner tumor with its characteristic imaging
features. A prominent fibrous stromal component may contribute to relatively
low T2 signal intensity and may also account for the lesion's solid morphology
and relatively low vascularity.
6. Epidemiology
Brenner tumor is an uncommon ovarian neoplasm.
According to the case material, most lesions may be small and discovered
incidentally in asymptomatic women. They are frequently identified in peri- or
postmenopausal women, although smaller lesions measuring less than 2 cm have
also been reported.
Table 1. Epidemiologic and Clinical Profile of Brenner
Tumor
|
Characteristic |
Typical Features |
|
Frequency |
Rare ovarian tumor |
|
Typical age |
More common in middle-aged
and older women |
|
Menopausal status |
May occur in peri- or
postmenopausal women |
|
Size |
Variable, ranging from small
lesions to large masses |
|
Symptoms |
Often asymptomatic or
associated with nonspecific pelvic symptoms |
|
Common symptoms |
Lower abdominal pain, pelvic
discomfort, pressure symptoms |
|
Sex |
Female |
|
Pathologic type |
Benign, borderline, or
malignant |
|
Prognosis |
Generally favorable in
benign tumors; malignant tumors depend on stage and extent of invasion |
However, precise incidence and prevalence estimates vary considerably
across the literature and among different study populations. Because Brenner
tumor is rare, stable population-level incidence estimates comparable to those
available for common ovarian cancers are difficult to establish.
7. Clinical Presentation
Most Brenner tumors are asymptomatic.
When symptoms occur, they may be nonspecific and include:
- Lower abdominal pain
- Pelvic discomfort
- Abdominal distension
- A sensation of pelvic
pressure
- Abnormal uterine bleeding
- Rarely, hormone-related
symptoms
In this case, the patient presented with left lower abdominal pain.
However, there is insufficient evidence to conclude that the 3–4 cm ovarian
mass identified on imaging was the direct cause of the pain.
Red Flags
The following findings should raise greater concern for a borderline or
malignant lesion rather than a simple benign Brenner tumor:
- Rapid interval growth
- Large tumor size
- Irregular solid
components
- Necrosis
- Marked contrast
enhancement
- Infiltrative margins
- Peritoneal nodules
- Lymphadenopathy
- Ascites
- Distant metastases
8. Imaging Features
8.1 CT Imaging
The most important CT finding in this case is a 3–4 cm calcified solid
mass arising from the left ovary.
Figure 3. Axial Contrast-Enhanced CT
Axial contrast-enhanced CT demonstrates a heterogeneous, relatively
hyperattenuating mass in the region of the left ovary. Small calcific foci are
scattered throughout the lesion. The absence of a definite macroscopic fat
component is an important feature when differentiating this lesion from a
mature cystic teratoma.
Radiologist Interpretation
The first point to establish is the origin of the mass.
The second is its composition.
Key questions include:
- Is the lesion solid?
- Is it cystic?
- Does it contain fat?
- Does it contain
calcification?
In this case, calcification is present, but there is no convincing
evidence of macroscopic fat.
Therefore, the simplistic equation—
Calcified ovarian mass = mature cystic teratoma
—is not an appropriate diagnostic approach.
8.2 Coronal CT
Figure 4. Coronal Contrast-Enhanced CT
Coronal reconstruction is useful for evaluating the relationship between
the mass, the uterus, and the bowel, and for tracing the lesion back to its
ovarian origin.
Particularly in small adnexal masses, the superior-to-inferior extent of
the lesion and its relationship to adjacent structures may be more clearly
appreciated on coronal images than on axial images.
Radiology Pearl
When evaluating a small ovarian mass, the first question should not be
“What does it look like?” but rather “Where did it originate?”
8.3 Sagittal CT
Figure 5. Sagittal Contrast-Enhanced CT
The sagittal plane allows assessment of the lesion's anterior-posterior
location and its relationship to the uterus and rectum.
This multiplanar approach can help determine whether a small calcified
mass truly originates from the ovary or instead arises from another pelvic
structure.
9. Ultrasound
Transvaginal ultrasound is a key imaging modality in the initial
evaluation of ovarian and adnexal masses.
In this case, the peripheral portion of the lesion appears echogenic and
produces prominent posterior acoustic shadowing. Color Doppler imaging
demonstrates little to no internal vascularity.
This appearance is important because it may closely resemble the classic
imaging pattern of a mature cystic teratoma.
In mature cystic teratoma, fat, hair, sebaceous material, and
calcification can all produce marked acoustic reflection and posterior
shadowing on ultrasound.
However, when CT fails to demonstrate convincing fat, the diagnosis should
be reconsidered.
Doppler
Low vascularity may serve as an additional clue suggesting a benign
lesion, but minimal blood flow does not exclude malignancy.
Management decisions should therefore never be based on a Doppler finding
alone.
O-RADS US is a standardized system
designed to describe adnexal lesions systematically and stratify the risk of
malignancy, using ultrasound as the primary imaging modality for evaluating
female pelvic masses.
10. MRI: The Decisive Tool for Tissue Characterization
MRI is the most important modality for tissue characterization in this
case.
The ACR O-RADS MRI system provides a structured approach for
further characterization of indeterminate adnexal lesions detected on
ultrasound and for assessment of malignant potential. It integrates information
from T1-weighted imaging, T2-weighted imaging, DWI, and contrast enhancement.
T1-Weighted Imaging
Figure 6. T1-Weighted MRI
T1-weighted imaging is used to assess for the presence of high-signal
components such as fat or blood products.
This is particularly important in suspected mature cystic teratoma, in
which the identification of fat is a key diagnostic clue.
T1-Weighted Fat-Suppressed Imaging
Figure 7. T1-Weighted Fat-Suppressed MRI
When a lesion demonstrates high signal intensity on T1-weighted imaging,
fat-suppressed sequences can help determine whether that signal represents fat.
One of the key features of this case is the absence of a definite fat
component that would strongly support the diagnosis of a mature cystic teratoma.
11. T2-Weighted MRI: Why Is the Lesion Dark?
Figure 8. T2-Weighted MRI
One of the most interesting imaging characteristics of Brenner tumor is
its tendency to demonstrate relatively low signal intensity on T2-weighted
imaging.
The primary reason is its dense fibrous stroma.
Collagen-rich tissue can restrict the mobility of free water and alter T2
relaxation characteristics, causing the tissue to appear relatively dark on
T2-weighted images.
The following conceptual relationship is therefore important:
Low T2 signal
→ Fibrous tissue
→ Consider Brenner tumor/fibroma/thecoma
The case material also identifies low T2 signal intensity as an important
clue that may help distinguish Brenner tumor from other nonfibrous ovarian
neoplasms.
However, low T2 signal is not a highly specific diagnostic finding when
considered in isolation.
12. T2-Weighted Fat-Suppressed MRI
Figure 9. T2-Weighted Fat-Suppressed MRI
T2-weighted fat-suppressed sequences may help distinguish the solid and
cystic components of a lesion more clearly.
In lesions containing abundant dense fibrous tissue, relatively low signal
intensity may persist on T2-weighted imaging.
13. DWI and ADC
Figure 10. DWI and ADC
Diffusion-weighted imaging evaluates the mobility of water molecules,
while the ADC map helps determine whether true diffusion restriction is
present.
A common interpretive error is:
High signal on DWI = cancer
This equation is incorrect.
T2 shine-through may occur, and benign lesions may also demonstrate
variable diffusion characteristics depending on their cellularity and tissue
composition.
Therefore, interpretation should integrate:
DWI + ADC + T2 + T1 + contrast enhancement
rather than relying on DWI alone.
The O-RADS MRI system likewise places greater emphasis on lesion
morphology and the characteristics of enhancing solid tissue than on isolated
DWI signal intensity.
14. Contrast Enhancement and the O-RADS Perspective
In the contemporary MRI evaluation of ovarian masses, assessment extends
beyond simply determining whether a lesion is “enhancing” or “non-enhancing.”
The morphology and degree of enhancement of enhancing solid tissue are
also important.
The O-RADS MRI system integrates the characteristics of enhancing solid
tissue, wall and septal morphology, T2 signal characteristics, and diffusion
findings to stratify the risk of malignancy.
Therefore, even when a Brenner tumor is suspected, the following questions
remain important:
- Does the solid component
truly enhance?
- Is the enhancement
homogeneous?
- Are irregular nodular
components present?
- Is necrosis present?
- Is there evidence of
invasion into adjacent structures?
- Are peritoneal nodules or
ascites present?
This approach is important because its purpose is not necessarily to
establish a definitive diagnosis of a rare tumor, but rather to provide a
structured assessment of the risk of malignancy.
15. Multimodal Imaging Comparison
|
Imaging Modality |
Strengths |
Limitations |
Clinical Value |
|
Ultrasound |
Accessibility, real-time
evaluation, Doppler assessment |
Limited tissue
characterization |
Initial evaluation and
morphologic assessment |
|
CT |
Evaluation of calcification,
fat, and metastatic disease |
Limited soft-tissue
characterization |
Assessment of lesion
composition and staging |
|
MRI T1 |
Evaluation of fat and blood
products |
Longer examination time |
Tissue component analysis |
|
MRI T1 Fat-Suppressed |
Confirmation of fat |
Limited specificity when
used alone |
Differentiation from
teratoma |
|
MRI T2 |
Assessment of fibrous tissue |
Nonspecific findings |
Evaluation of fibrous tumors |
|
DWI |
Assessment of cellularity
and diffusion characteristics |
T2 shine-through |
Adjunctive assessment of
malignant potential |
|
ADC |
Confirmation of true
diffusion restriction |
Overlap between benign and
malignant lesions |
Complementary interpretation
of DWI |
|
Contrast-Enhanced MRI |
Evaluation of enhancing
solid tissue |
Requires contrast
administration |
Malignancy risk
stratification |
16. Imaging Differential Diagnosis
|
Diagnosis |
CT |
MRI |
Pathology |
Key Differential Point |
|
Brenner tumor |
Solid; may contain
calcification |
May demonstrate low T2
signal |
Transitional/urothelial-like
nests with fibrous stroma |
Calcification + low T2
signal + absence of convincing fat |
|
Mature cystic teratoma |
Fat + calcification |
Fat signal |
Diverse germ-cell components |
Fat is the decisive imaging
clue |
|
Ovarian fibroma |
Solid |
Low T2 signal |
Fibrous stroma |
Considerable overlap with
Brenner tumor |
|
Thecoma |
Solid |
May demonstrate low T2
signal |
Theca cells with fibrous
tissue |
Hormonal manifestations may
provide an additional clue |
|
Serous tumor |
May be cystic or mixed
cystic-solid |
Variable |
Epithelial tumor |
Papillary or enhancing solid
tissue |
|
Mucinous tumor |
Multiloculated cystic mass |
Variable T2 signal |
Mucin-producing epithelium |
Multiloculated cystic
architecture |
|
Malignant Brenner tumor |
Large, heterogeneous solid
mass; possible necrosis |
Enhancing solid tissue |
Malignant urothelial-like
component |
Invasion, metastasis,
ascites |
The case material also identifies mature cystic teratoma, fibroma,
thecoma, serous and mucinous tumors, and malignant Brenner tumor as important
differential diagnoses.
17. The Most Important Differential Diagnosis: Mature
Cystic Teratoma
The most important diagnostic pitfall in this case is reaching a premature
conclusion of mature cystic teratoma simply because calcification is
present.
One of the most important imaging features supporting mature cystic
teratoma is fat.
By contrast, the following combination should prompt reconsideration of
Brenner tumor and other fibrous ovarian tumors:
- Calcification
- Solid morphology
- No convincing fat
- Low vascularity
- Low T2 signal
This is the central imaging pattern of the present case.
18. Benign vs Borderline vs Malignant Brenner Tumor
Most Brenner tumors are benign.
However, malignant Brenner tumor, although extremely rare, is clinically
important.
Imaging findings that should raise suspicion for malignancy include:
- Large tumor size
- Irregular solid
components
- Necrosis
- Marked contrast
enhancement
- Infiltrative margins
- Peritoneal dissemination
- Lymphadenopathy
- Ascites
- Distant metastases
Recent pathologic studies have identified molecular features of malignant
Brenner tumors, including CDKN2A/B loss and alterations involving FGFR3-driven
pathways or MDM2/TP53-related mechanisms.
A 2026 study also reported CDKN2A/CDKN2B deletion, MDM2 amplification, and
alterations involving KRAS, PIK3CA, and FGFR3 in borderline and malignant
Brenner tumors, highlighting their molecular heterogeneity.
19. Radiologist's Reading Report
Findings
An approximately 3–4 cm heterogeneous solid mass is identified in the left
adnexal/ovarian region. Small internal calcific foci are present. No definite
macroscopic fat component is identified based on the provided CT and MRI
descriptions.
On transvaginal ultrasonography, the lesion demonstrates echogenic
components with prominent posterior acoustic shadowing and minimal internal
Doppler vascularity.
On MRI, the lesion demonstrates relatively low T2 signal intensity,
compatible with a fibrous tissue-rich component. DWI and ADC findings should be
interpreted in conjunction with lesion morphology and enhancement
characteristics.
No definite imaging evidence of peritoneal dissemination, significant
lymphadenopathy, or ascites is described in the provided case material.
Impression
Small calcified solid mass of the left ovary with low T2 signal intensity
and minimal vascularity.
The combination of calcification, absence of convincing macroscopic fat,
solid morphology, and low T2 signal raises the possibility of a Brenner
tumor, particularly a benign lesion with abundant fibrous stroma.
Mature cystic teratoma remains an important differential diagnosis.
However, the absence of definite fat makes a classic mature cystic teratoma
less convincing.
Histopathologic confirmation is required for a definitive diagnosis.
20. Clinical Correlation
Suspecting a Brenner tumor on imaging and establishing a definitive
diagnosis of Brenner tumor are two different stages of clinical evaluation.
Imaging can provide important information regarding the nature of the
tumor and the risk of malignancy, but the final diagnosis is established
through pathologic evaluation.
Therefore, the purpose of a radiology report is not simply to place the
name “Brenner tumor” into the differential diagnosis.
More importantly, the report should explain:
- Why the lesion is
considered more likely to be benign.
- Which alternative
diagnoses should be considered.
- Which imaging findings,
if present, would raise concern for malignancy.
21. Treatment
Treatment should be determined by integrating multiple factors, including
the pathologic type of the tumor, the patient's age and menopausal status,
symptoms, tumor size, interval growth, imaging features suggesting malignancy,
and the need for ovarian preservation.
Even when a lesion is small and appears likely to be benign on imaging,
gynecologic evaluation may be appropriate depending on the clinical context.
When surgery is performed, histopathologic examination provides the
definitive diagnosis. If malignancy is suspected, oncologic surgical principles
become more important than simple local excision.
Because Brenner tumor is rare, applying a single uniform treatment
algorithm to every patient is less appropriate than individualized,
multidisciplinary decision-making.
22. Prognosis
The prognosis of benign Brenner tumor is generally favorable.
Borderline and malignant Brenner tumors, however, have distinct clinical
implications. Although malignant Brenner tumor is rare, it may progress as
invasive or metastatic disease, and prognosis is influenced by tumor stage and
the presence or absence of residual disease.
Recent pathologic literature continues to explore the molecular and
morphologic distinctions between benign or borderline tumors and malignant
Brenner tumors. Advanced malignant Brenner tumors may be associated with a
substantial risk of recurrence.
23. The Artificial Intelligence Perspective
Brenner tumor is also an interesting disease from the perspective of
artificial intelligence.
The principal challenge is data scarcity.
Because Brenner tumor is extremely rare, constructing large supervised
deep-learning datasets is difficult.
What AI May Be Able to Detect First
AI systems may automatically quantify features such as:
- Lesion segmentation
- Lesion volume
- Calcification
- Solid-to-cystic ratio
- T2 signal intensity
- ADC distribution
- Enhancement kinetics
- Vascularity
- Peritoneal nodularity
- Lymph node morphology
Radiomics
Radiomics transforms imaging features that are often assessed
qualitatively by the human eye into quantitative variables.
Examples include:
- Intensity histograms
- Texture features
- Entropy
- Homogeneity
- Shape characteristics
- Gray-level co-occurrence
matrix features
- ADC histogram analysis
- Enhancement heterogeneity
By combining these features, it may be possible to develop models for
predicting benign versus borderline/malignant risk.
However, in rare tumors such as Brenner tumor, overfitting and dataset
shift represent major challenges.
24. Foundation Models and Vision-Language Models
In the future, multimodal foundation models may play a more important role
than AI systems designed solely to classify a specific tumor type.
For example, if an AI system could simultaneously analyze:
CT + MRI + Ultrasound + Pathology + Laboratory Data + Clinical History
it could potentially move beyond simple image classification toward more
sophisticated clinical reasoning support.
A vision-language model could process a clinical description such as:
“A 53-year-old woman with a 3–4 cm calcified solid lesion in the left
ovary, minimal vascularity, no convincing macroscopic fat, and low T2 signal.”
Based on this information, the AI system could propose a differential
diagnosis that includes:
- Brenner tumor
- Ovarian fibroma
- Thecoma
- Mature cystic teratoma
It could also provide the reasoning supporting each possibility and
recommend additional MRI sequences or imaging information that may help refine
the differential diagnosis.
However, this should be understood as clinical decision support,
not diagnostic automation.
25. AI Workflow
Figure 11. AI-Assisted Brenner Tumor Imaging Workflow
Figure Legend
Ultrasound → PACS → AI lesion detection → CT/MRI tissue characterization →
Radiomics → Multimodal clinical integration → O-RADS risk stratification →
Radiologist review → Structured report → Multidisciplinary management
Image Prompt
Enterprise radiology AI workflow for ovarian adnexal mass evaluation,
showing ultrasound and CT/MRI entering PACS, AI segmentation, radiomics, multimodal
foundation model, O-RADS risk stratification, radiologist validation,
structured report and multidisciplinary gynecologic oncology decision support,
professional medical technology infographic.
26. Enterprise AI, PACS, HL7, and FHIR
In a real hospital environment, algorithmic accuracy alone is not
sufficient for successful AI implementation.
AI systems must be integrated with PACS, imaging data must be processed
using DICOM-based workflows, and clinical information and laboratory results
must be connected with hospital information systems.
If FHIR-based interoperability is established, AI may have greater
potential to incorporate clinical context rather than analyzing images in
isolation.
However, several challenges remain important in real-world deployment:
- Data governance
- Patient privacy
- Cybersecurity
- Model drift
- Bias
- Explainability
- Human oversight
- Regulatory compliance
This is particularly important in rare tumors, where the training dataset
itself may be heavily biased toward specific institutions, scanners, imaging
protocols, or patient populations.
27. The Future of Precision Medicine
Radiogenomics
By linking MRI phenotypes with molecular alterations, future research may
enable the noninvasive prediction of molecular subtypes of Brenner tumor.
Digital Twin
As virtual patient models integrating imaging, pathology, molecular
information, and treatment response continue to evolve, new approaches may
emerge for simulating potential treatment strategies.
Federated Learning
For rare tumors, federated learning is particularly attractive because
multiple hospitals may collaboratively train AI models without directly sharing
patient-level data.
Synthetic Data
Because real-world Brenner tumor datasets are limited, synthetic imaging
data may potentially be used to expand research datasets.
However, if synthetic data fail to adequately capture the biological diversity
of real patients, they may instead introduce or amplify bias.
Multimodal AI
Ultimately, one of the most important future directions may be multimodal
AI integrating:
Imaging + Pathology + Genomics + Clinical Data
Clinical Pearls
- Ovarian calcification
does not necessarily indicate a mature cystic teratoma.
- More important than the
presence of calcification itself is the tissue in which the calcification
occurs.
- If macroscopic fat is
absent on CT, the possibility of a classic mature cystic teratoma should
be reconsidered.
- Brenner tumor may present
as a solid ovarian mass.
- Dense fibrous stroma may
be associated with low T2 signal intensity.
- Low T2 signal is not
specific for Brenner tumor.
- Ovarian fibroma is an
important differential diagnosis.
- Thecoma may also
demonstrate low T2 signal.
- High signal intensity on
DWI alone should not be used to diagnose malignancy.
- ADC should be interpreted
together with DWI.
- Irregular solid
components and necrosis increase concern for malignancy.
- Peritoneal dissemination,
lymphadenopathy, and ascites are highly important from a staging
perspective.
- Small Brenner tumors may
be discovered incidentally in asymptomatic patients.
- Definitive diagnosis
requires pathologic evaluation.
- The central role of
radiology is not simply to name a tumor, but to provide a structured
assessment of malignancy risk.
Quiz
Question 1
A 53-year-old woman is found to have a 3–4 cm calcified solid mass in the
left ovary. CT demonstrates no definite macroscopic fat, while ultrasound shows
prominent posterior acoustic shadowing and low internal vascularity.
Which of the following is the most appropriate diagnosis?
① Serous cystadenoma
② Mucinous cystadenoma
③ Mature cystic teratoma
④ Ovarian fibroma
⑤ Brenner tumor
Answer: ⑤ Brenner tumor
Explanation: Although
calcification and acoustic shadowing may initially suggest a teratoma, the
absence of definite fat, together with solid morphology, low vascularity, and
low T2 signal intensity, makes Brenner tumor an important differential
diagnosis.
Question 2
Which histologic feature is most closely associated with relatively low
signal intensity on T2-weighted MRI in Brenner tumor?
① Mucin
② Fat
③ Hemorrhage
④ Dense fibrous stroma
⑤ Simple serous fluid
Answer: ④ Dense fibrous stroma
Explanation: The fibrous
stroma of Brenner tumor is associated with low T2 signal intensity. However,
this finding alone is not sufficient to establish the diagnosis of Brenner
tumor.
Question 3
Which combination of imaging findings should raise the strongest suspicion
for malignant Brenner tumor?
① Uniform calcification in a lesion measuring less than 2 cm
② Marked posterior acoustic shadowing
③ Low T2 signal intensity
④ Irregular solid components with peritoneal dissemination
⑤ A small lesion with minimal internal vascularity
Answer: ④ Irregular solid components with peritoneal
dissemination
Explanation: Irregular solid
components, necrosis, invasion, peritoneal dissemination, lymphadenopathy, and
ascites are important findings that increase concern for malignancy.
Question 4
Which of the following is the most useful clue for differentiating mature
cystic teratoma from Brenner tumor?
① Assessing only whether calcification is present
② Assessing only whether the patient has pain
③ Evaluating the presence of macroscopic fat on CT or MRI
④ Making the diagnosis based solely on the patient's age
⑤ Relying only on high signal intensity on DWI
Answer: ③ Evaluating the presence of macroscopic fat on
CT or MRI
Explanation: Fat is a key
imaging feature of mature cystic teratoma. In a calcified solid ovarian mass
without convincing fat, other lesions, including Brenner tumor, should be
considered.
Frequently Asked Questions
Q1. Is Brenner tumor a cancer?
Most Brenner tumors are benign, but borderline and malignant Brenner
tumors do exist.
Q2. Does calcification in the ovary always indicate a
teratoma?
No. Calcification may occur in several different ovarian tumors.
Q3. What is the most important MRI feature of a Brenner
tumor?
Relatively low T2 signal intensity associated with its fibrous stroma is
an important imaging clue.
Q4. Does low T2 signal mean that the lesion is a Brenner
tumor?
No. Other fibrous ovarian tumors, including ovarian fibroma and thecoma,
may also demonstrate low T2 signal intensity.
Q5. Does high signal on DWI indicate malignancy?
No. DWI findings must be interpreted together with ADC values and other
MRI sequences.
Q6. In which age group does Brenner tumor most commonly
occur?
It tends to occur in middle-aged and older women, particularly around or
after menopause.
Q7. Can Brenner tumor be asymptomatic?
Yes. Small lesions may be discovered incidentally.
Q8. Which is better, CT or MRI?
They serve different purposes. CT is useful for evaluating calcification,
fat, peritoneal disease, and staging, whereas MRI provides superior tissue
characterization and assessment of solid tissue.
Q9. Can imaging establish the final diagnosis?
Imaging can provide a strong diagnostic direction, but definitive
diagnosis requires pathologic evaluation.
Q10. Can AI diagnose Brenner tumor?
At present, AI should not be regarded as a clinically established
standalone diagnostic tool for Brenner tumor. In the future, radiomics and
multimodal AI may contribute to risk stratification and clinical decision
support.
Conclusion
Brenner tumor is not a neoplasm commonly encountered in routine radiologic
practice.
Yet it is precisely because of its rarity that subtle imaging clues may be
overlooked.
In this case of a 53-year-old woman, the key finding was not simply that calcification
was present.
What truly mattered was the following combination:
- Left ovarian origin
- Small solid mass
- Calcification
- Absence of convincing
macroscopic fat
- Marked acoustic shadowing
on ultrasound
- Low vascularity
- Low signal intensity on
T2-weighted MRI
This pattern shifts the radiologist's diagnostic reasoning away from the
classic fat-containing appearance of a mature cystic teratoma.
The case also illustrates a broader and more important principle.
Imaging diagnosis is not the process of identifying a single finding. It
is the process of integrating multiple findings with the underlying
pathophysiology.
Do not diagnose a teratoma simply because calcification is present.
Do not establish the diagnosis of Brenner tumor simply because the lesion
is dark on T2-weighted MRI.
Do not declare a lesion malignant simply because it demonstrates high
signal on DWI.
Instead, integrate CT, ultrasound, MRI, DWI/ADC, contrast enhancement,
patient age, and clinical information into a single coherent imaging pattern.
The current O-RADS MRI framework supports this structured approach by
facilitating assessment of tissue characteristics and enhancing solid tissue
within adnexal lesions and by stratifying the risk of malignancy.
Ultimately, the best radiology report for a suspected Brenner tumor does
not simply state:
“Possible Brenner tumor.”
A better report explains why the diagnosis is being considered, which
alternative diagnoses should remain in the differential, and which
imaging findings would increase concern for malignancy.
This is the point at which radiology moves beyond simple image recognition
and becomes a meaningful component of clinical decision-making.
What Does a Calcified Ovarian Mass with Low T2 Signal Mean?
A calcified ovarian mass with
low T2 signal may represent a fibrous ovarian tumor, such as a Brenner tumor or
ovarian fibroma. If macroscopic fat is absent, a classic mature cystic teratoma
becomes less convincing. MRI, particularly T2-weighted and fat-suppressed
sequences, DWI/ADC, and contrast-enhanced imaging, can improve lesion
characterization, but definitive diagnosis requires pathologic evaluation.
Frequently
Asked Questions About Brenner Tumors
What
is a Brenner tumor?
A Brenner tumor is a rare
ovarian epithelial tumor characterized histologically by urothelial-like
epithelial nests embedded within a fibrous stroma.
Can
a Brenner tumor contain calcification?
Yes. Calcification can occur
in Brenner tumors and may provide an important imaging clue.
Why
does a Brenner tumor appear dark on T2-weighted MRI?
Its dense fibrous stroma can
produce relatively low signal intensity on T2-weighted MRI.
Is a
Brenner tumor malignant?
Most Brenner tumors are
benign. However, borderline and malignant forms also exist.
What
is the most important differential diagnosis?
Important differential
diagnoses include mature cystic teratoma and other fibrous ovarian tumors,
particularly ovarian fibroma and thecoma.
References
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Medical Disclaimer
This content is intended for educational purposes in radiology and medicine
and is not a substitute for an individual patient's diagnosis or treatment.
Clinical decisions for actual patients should be based on a comprehensive
assessment of the patient's clinical condition, imaging findings, pathologic
evaluation, and the judgment of the treating physician or relevant specialist.
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