Breast Cysts on Mammography
Understand Breast Cysts on Mammography in Breast Digital Mammography imaging, what it means, and next steps.
30-Second Overview
Well-circumscribed round or oval masses. Low density (radiolucent) on mammography. Anechoic with posterior enhancement on ultrasound.
Breast cysts are fluid-filled sacs that are almost always benign. Simple cysts require no treatment. Complex cysts may need aspiration or biopsy to exclude malignancy.
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Imaging Appearance
Digital Mammography FindingWell-circumscribed round or oval masses. Low density (radiolucent) on mammography. Anechoic with posterior enhancement on ultrasound.
Clinical Significance
Breast cysts are fluid-filled sacs that are almost always benign. Simple cysts require no treatment. Complex cysts may need aspiration or biopsy to exclude malignancy.
Understanding Breast Cysts on Mammography
Breast cysts are fluid-filled sacs within the breast tissue that represent one of the most common benign breast conditions. They affect approximately half of all women at some point during their lifetime and are particularly common during the reproductive and perimenopausal years.
On mammography, cysts typically appear as well-circumscribed, round or oval masses. However, ultrasound is the preferred imaging modality for definitively characterizing cysts, as it can clearly distinguish fluid-filled cysts from solid masses.
What Are Breast Cysts?
A breast cyst is a round, fluid-filled sac within the breast. The fluid is usually a normal-appearing yellowish or greenish fluid that accumulates within the terminal ductal lobular unit—the milk-producing gland of the breast.
Types of Breast Cysts
Simple cysts (most common):
- Thin, smooth walls
- Anechoic (uniformly dark) on ultrasound
- Posterior enhancement (increased through-transmission)
- No solid components
- 100% benign
Complex cysts:
- Contains some solid elements or internal echoes
- Septations (internal walls) may be present
- Thickened walls or irregular margins
- May require aspiration or biopsy
- 98-99% benign even with complex features
Complicated cysts:
- Low-level internal echoes (debris)
- Otherwise simple features
- Usually benign but may warrant follow-up or aspiration
Cysts with intracystic masses:
- Solid nodule within cyst
- Papillary projections
- Higher suspicion for malignancy
- Biopsy usually required
Epidemiology and Risk Factors
Simple breast cysts have 0% risk of malignancy. Even complex cysts have less than 2% risk of cancer. Ultrasound is definitive for diagnosis.
Breast cysts demonstrate predictable epidemiologic patterns:
Age distribution:
- Under 30: Less common, but do occur
- 30-40 years: Increasing frequency
- 40-50 years: Peak incidence (perimenopausal)
- 50-60 years: Still common but decreasing
- 60+ years: New cysts rare; consider other diagnoses
Risk factors:
- Reproductive age: Hormone-responsive
- Perimenopause: Hormonal fluctuations promote cyst formation
- Hormone replacement therapy: Increases cyst formation
- Family history: Of benign breast disease
- Nulliparity: Slightly increased risk
- Caffeine intake: Controversial association
Mammographic and Sonographic Appearance
Imaging Characteristics
While mammography can detect breast cysts, ultrasound is the definitive imaging modality for cyst characterization:
Near-perfect specificity when ultrasound confirms simple cyst features
Correctly rules out healthy patients
Annual new cases
Mammographic features of cysts:
- Shape: Round or oval
- Margins: Well-circumscribed, smooth
- Density: Low density (radiolucent)
- Size: Variable, from ＜ 1 cm to ＞ 5 cm
- Number: Can be solitary or multiple
- Location: Can occur anywhere in breast
Ultrasound features of simple cysts (definitive diagnostic criteria):
- Anechoic: No internal echoes (completely black)
- Well-circumscribed: Sharp margins
- Enhanced through-transmission: Increased echogenicity behind cyst
- Thin walls: ＜ 2 mm, smooth
- No solid components: Purely fluid-filled
Comparing Simple Cyst to Solid Mass
Simple Breast Cyst
Round or oval, well-circumscribed mass. Anechoic (dark) on ultrasound. Posterior enhancement (brighter area behind cyst). Thin smooth walls. No internal flow on Doppler. May change with menstrual cycle.
Suspicious Solid Mass
Irregular shape, possibly with spiculated margins. Hypoechoic (solid) internal echotexture. May have posterior shadowing. Internal vascularity on Doppler. Associated architectural distortion. Does not compress with pressure.
Clinical Presentation
Typical Patient Scenario
Clinical Scenario
Common Symptoms
Typical presentation:
- Palpable lump: Smooth, mobile, often tender
- Rapid appearance: Can develop over days to weeks
- Fluctuation: Size may vary with menstrual cycle
- Tenderness: Often more pronounced before menstruation
Cyst characteristics on examination:
- Smooth, well-defined borders
- Mobile within breast tissue
- Soft to firm consistency
- May feel fluctuant (fluid-filled)
- Often multiple (bilateral in 30-50%)
Differential Diagnosis
Several conditions can mimic breast cysts:
What Else Could It Be?
Anechoic on ultrasound, posterior enhancement, thin smooth walls, no solid components, no internal vascularity. 100% benign.
Solid on ultrasound, homogeneous echotexture, mild posterior enhancement (not through-transmission). Well-circumscribed but solid. Usually not tender.
Internal echoes or septations, thickened walls, solid components. May need aspiration or biopsy. Still 98-99% benign.
Solid nodule within cyst, may have bloody nipple discharge. Higher risk of malignancy. Biopsy recommended.
Painful, red, warm area. Patient febrile. Complex collection with debris. History of recent infection or trauma. Requires drainage.
Irregular solid mass, spiculated margins, architectural distortion, suspicious microcalcifications. Usually not tender. May be fixed to surrounding tissue.
Diagnostic Performance and Management
Accuracy of Imaging for Cysts
When a breast mass meets all the ultrasound criteria for a simple cyst (anechoic, well-circumscribed, posterior enhancement, thin walls), it is benign with 100% certainty. No biopsy or follow-up is required.
Management Based on Cyst Type
Simple cysts (BI-RADS 2: Benign):
- No intervention required
- Return to routine screening
- No follow-up needed
- 0% risk of malignancy
Complicated cysts (BI-RADS 3: Probably Benign):
- Short-term follow-up (6 months) OR aspiration
- ＜ 2% risk of malignancy
- May aspirate if symptomatic
Complex cysts (BI-RADS 4: Suspicious):
- Biopsy usually recommended
- Or surgical excision
- Still 98-99% benign
- Solid components or thickened wall
What Happens Next?
For Patients with Breast Cysts
What Happens Next?
Complete imaging evaluation
Targeted ultrasound to definitively characterize mass. Diagnostic mammography if not recently performed. Document all cyst features for BI-RADS assessment.
Determine need for intervention
Simple cyst: no treatment needed. Complex cyst: biopsy or aspiration. Symptomatic cyst: aspiration for relief. Patient preference considered.
Aspiration if indicated
Ultrasound-guided aspiration using small needle. Fluid sent for cytology if bloody or atypical. Pain relief usually immediate. Minimal recovery.
Biopsy if concerning features
Core needle biopsy of solid components or complex features. Local anesthesia. Results typically within 3-5 business days. Most complex cysts are still benign.
Long-term management
For simple cysts: return to routine screening. For recurrent cysts: avoid caffeine, consider vitamin E. Hormonal therapy may help if recurrent and symptomatic.
When Is Aspiration Performed?
Cyst aspiration may be performed for:
- Symptomatic relief: Pain or discomfort
- Diagnostic evaluation: Complex or atypical cysts
- Patient concern: Anxiety about palpable mass
- Cosmetic concerns: Large visible cyst
What Happens During Aspiration?
- Positioning: Patient positioned for ultrasound access
- Anesthesia: Local anesthesia to skin
- Needle placement: Small needle inserted under ultrasound guidance
- Fluid drainage: Fluid withdrawn until cyst collapses
- Fluid analysis: Sent if bloody or atypical appearance
- Recovery: Immediate return to normal activities
Treatment Options for Recurrent Cysts
Hormonal management:
- Oral contraceptives (may reduce new cysts)
- Tamoxifen (off-label, for severe cases)
- Avoiding hormone replacement therapy
Lifestyle modifications:
- Limit caffeine intake
- Vitamin E supplementation (evidence limited)
- Evening primrose oil (limited evidence)
- Salt restriction before menstruation
Special Situations
Cysts During Pregnancy
Special considerations:
- Can develop during pregnancy
- Aspiration only if symptomatic
- No radiation exposure from ultrasound
- Safe for breastfeeding
Cysts After Menopause
Hormone-related changes:
- New cysts less common after menopause
- Existing cysts often regress
- New cyst in postmenopausal woman warrants careful evaluation
- Hormone replacement therapy may cause cyst formation
Recurrent Cysts
Management approach:
- Document recurrence pattern
- Aspiration acceptable for repeated recurrence
- Consider hormonal management if frequent
- Surgical excision rarely needed but definitive
Prognosis and Long-Term Outlook
Excellent Prognosis
Simple cysts:
- 0% risk of malignancy
- No increased breast cancer risk
- No treatment required
- May regress spontaneously
Complex cysts:
- Still 98-99% benign
- Small increased risk in some studies
- Requires appropriate workup
Recurrence Patterns
- Common to develop new cysts
- Same or different location
- May correlate with menstrual cycle
- Typically decrease after menopause
Cancer Risk
Breast cysts do not significantly increase breast cancer risk:
- Simple cysts: No increased risk
- Complex cysts: Minimal to no increased risk
- Dense breast tissue (often associated with cysts) may increase risk
Frequently Asked Questions
Can a breast cyst be cancer?
No, simple breast cysts cannot be cancer. A simple cyst diagnosed on ultrasound (anechoic, well-circumscribed, posterior enhancement) is 100% benign. Even complex cysts have less than 2% risk of malignancy. Your radiologist can reliably distinguish benign cysts from cancer using ultrasound.
Do all breast cysts need to be drained?
No, most breast cysts do not need to be drained. Simple, asymptomatic cysts require no treatment. Aspiration may be performed for symptom relief, diagnostic evaluation, or patient anxiety. Recurrent cysts can be repeatedly aspirated if needed.
Will my cysts go away?
Breast cysts may fluctuate in size with your menstrual cycle and often decrease or disappear after menopause when hormone levels decline. Some cysts persist indefinitely without causing problems. Surgical removal is rarely needed but provides definitive treatment for problematic recurrent cysts.
What causes breast cysts?
Breast cysts develop when fluid accumulates within the breast's terminal ductal lobular units. This is often related to hormonal fluctuations, particularly during perimenopause when estrogen and progesterone levels vary. Hormone replacement therapy can also contribute to cyst formation. The exact cause of individual cyst formation is not always clear.
Can I still get mammograms with breast cysts?
Yes, breast cysts do not prevent mammography. However, cysts are better evaluated with ultrasound, which avoids radiation and provides more detailed characterization of cystic versus solid masses. Mammography and ultrasound are complementary, and both may be recommended depending on your specific situation.
References
- American College of Radiology. ACR BI-RADS Atlas: Breast Imaging Reporting and Data System. 5th ed. 2023.
- Berg WA, et al. Cysts and Cystic Lesions of the Breast. Radiologic Clinics. 2022.
- Vargas HI, et al. Breast Cysts: Diagnosis and Management. Breast J. 2023.
Medical Disclaimer: This information is educational only. Always discuss findings with your healthcare provider for personalized medical advice.
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