From the Guidelines
A complex breast cyst is a fluid-filled sac within the breast that has some discrete solid component, which may include thick walls, thick septa, and/or intracystic mass, and is characterized by both anechoic (cystic) and echogenic (solid) components. Complex cysts require medical evaluation because they have a relatively high risk of malignancy, with studies showing a risk of 14% and 23% in two separate studies 1. If you discover a breast lump, you should see your healthcare provider who will likely order imaging tests such as an ultrasound or mammogram to characterize the cyst. Depending on the appearance, your doctor may recommend a fine needle aspiration or biopsy to examine the fluid or tissue. Most complex cysts are benign and may be caused by fibrocystic changes, inflammation, or injury to the breast tissue. However, proper evaluation is essential because complex cysts may be associated with malignancy. The NCCN Panel recommends a tissue (core needle) biopsy for complex (cystic and solid) masses (BI-RADS 4–5) 1.
Key Characteristics of Complex Breast Cysts
- Have some discrete solid component
- May include thick walls, thick septa, and/or intracystic mass
- Characterized by both anechoic (cystic) and echogenic (solid) components
- Require medical evaluation due to relatively high risk of malignancy
Recommended Evaluation and Management
- Imaging tests such as ultrasound or mammogram to characterize the cyst
- Fine needle aspiration or biopsy to examine the fluid or tissue
- Tissue (core needle) biopsy for complex (cystic and solid) masses (BI-RADS 4–5) 1
- Monitoring with follow-up imaging or surgical removal if there are concerning features
From the Research
Definition of Complex Breast Cyst
- A complex breast cyst is defined as a cyst in the breast containing a thick wall, internal septations, or a solid intracystic component 2.
- It is also referred to as a complex solid and cystic breast mass, which carries a malignant potential between 23-31% and thus requires further evaluation with biopsy 2.
Characteristics of Complex Breast Cysts
- Complex breast cysts are estimated to be reported in approximately 5% of breast ultrasound examinations 3.
- Ultrasound features associated with a higher risk of the lesion being a cancer include: thickened walls, thick internal septations, a mix of cystic and solid components, and an imaging classification of indeterminate 3.
- Sonographic complicated cysts are defined as those meeting most but not all criteria for simple cysts, similar to current Breast Imaging Reporting and Data System classification 4.
Management of Complex Breast Cysts
- The malignancy rate for complex breast cysts is relatively low, ranging from 0.3% to 0.4% 3, 4, 5.
- Management recommendations for complex breast cysts include follow-up imaging studies, sonographically guided aspiration, aspiration with possible core biopsy, and excisional biopsy 5.
- The use of ultrasound-guided percutaneous biopsy may be effective in diagnosing and guiding management of complex cystic masses, especially when the biopsy approach is tailored to the individual patient and imaging features are closely correlated with findings at pathologic analysis 6.