Management of Breast Cysts
Breast cysts should be managed based on their ultrasound classification: simple cysts require no intervention beyond routine screening, complicated cysts can be managed with either aspiration or 6-12 month surveillance for 1-2 years, and complex cysts mandate core needle biopsy due to their 14-23% malignancy risk. 1
Classification and Risk-Based Management
Breast cysts are categorized into three distinct types with different malignancy risks and management pathways:
Simple Cysts (Benign - No Malignancy Risk)
Ultrasound characteristics: 2
- Anechoic (completely fluid-filled)
- Well-circumscribed with imperceptible wall
- Round or oval shape
- Posterior acoustic enhancement
- No further imaging or intervention required if asymptomatic
- Return to routine screening mammography
- Therapeutic aspiration is optional only if the patient has persistent pain or discomfort 2, 3
- Aspirated fluid can be discarded if clear and non-bloody 4
Complicated Cysts (Very Low Risk - <2% Malignancy)
Ultrasound characteristics: 2
- Contains low-level internal echoes or debris
- Round, circumscribed mass
- No vascular flow on Doppler
- Fulfills most but NOT all criteria of simple cyst
- Critically: NO solid components, thick walls, or thick septa
Management options (choose one): 2, 1
- Option 1: Aspiration with cytology if bloody fluid obtained 2
- Option 2: Short-term surveillance with physical examination and ultrasound ± mammography every 6-12 months for 1-2 years 2, 1
- Aspiration may be preferred if patient is likely to be lost to follow-up 2
- Proceed to biopsy if the cyst increases in size during surveillance 2, 1, 3
Complex Cysts (High Risk - 14-23% Malignancy)
Ultrasound characteristics: 2, 5
- Discrete solid components present
- Thick walls (perceptible)
- Thick septations (≥0.5 mm)
- Intracystic masses
- Mixed cystic and solid appearance
- Core needle biopsy is mandatory (BI-RADS category 4-5)
- Do NOT attempt aspiration alone
- Ultrasound-guided biopsy is preferred when lesion is visible on ultrasound 3
Special Clinical Scenarios
Bloody Aspirate
If blood is obtained during cyst aspiration: 1
- Place tissue marker
- Send fluid for cytologic evaluation
- If cytology positive: percutaneous vacuum-assisted biopsy or surgical excision
- If cytology negative: physical examination ± ultrasound/mammogram every 6-12 months for 1-2 years
Post-Aspiration Persistent Mass
If a mass persists after attempted cyst aspiration: 2
- Proceed to ultrasound-guided core needle biopsy
- This indicates the lesion is not a simple cyst
Recurrent Cysts
For complicated cysts that recur after aspiration: 2
- Consider core needle biopsy rather than repeat aspiration
- Alternatively, continue surveillance if imaging characteristics remain benign
Common Pitfalls to Avoid
Do not aspirate complex cysts: 5
- 18 of 79 (23%) complex cystic lesions proved malignant in one series
- Aspiration delays definitive diagnosis
Do not send clear cyst fluid for cytology: 4, 6
- Only bloody or extremely tenacious fluid requires cytologic examination
- Clear fluid from simple cysts can be discarded
Do not rely on clinical examination alone: 3
- Only 58% of palpable cysts are correctly identified by physical examination
- Ultrasound characterization is essential
Do not perform routine cytology on simple cysts: 2, 6
- Simple cysts meeting all ultrasound criteria are benign
- Cytology adds no value and increases cost
Age-Specific Considerations
Women younger than 30 years: 2, 3
- Ultrasound is the preferred initial imaging modality
- Higher breast tissue density makes mammography less sensitive
- Lower radiation exposure
Women 30 years and older: 2
- Diagnostic mammogram should be performed first
- Ultrasound as adjunct for masses with BI-RADS 1-3 on mammography
Return to Routine Screening
Patients can return to routine screening when: 1, 3
- Simple cysts remain asymptomatic
- Complicated cysts remain stable after 1-2 years of surveillance
- Benign concordant biopsy results with stable imaging at 6-12 months