A breast cyst is a common, fluid-filled sac that develops within the breast tissue. These sacs are typically benign. While many breast cysts are simple, appearing as smoothly outlined, fluid-filled structures, a specific type known as a “complex cyst” warrants closer medical attention. Complex cysts differ from simple cysts due to features observed during imaging, requiring further evaluation.
Characteristics of Complex Cysts
Complex cysts are identified by specific features on medical imaging, especially on ultrasound. Unlike simple cysts, complex cysts often display irregular walls, internal divisions (septations), or solid components within the fluid. Solid components can appear as mural nodules, growths attached to the cyst wall.
The fluid might also contain debris, making the internal appearance less uniform. Radiologists categorize complex cysts based on their sonographic features, such as the thickness of their walls or septa, or the proportion of solid to cystic components. Some complex cysts might have thick walls or septa, or be predominantly solid.
Evaluation and Diagnosis
When a complex cyst is suspected, a diagnostic pathway is typically followed. Mammography and ultrasound are often the first imaging tests used to visualize breast lumps and determine if they are fluid-filled or solid. If the mass appears solid or has a combination of fluid and solid components, further evaluation is recommended.
Magnetic Resonance Imaging (MRI) may also be used for further assessment. The definitive diagnosis of a complex cyst often requires a biopsy, which involves taking tissue samples for laboratory analysis. This can be done through fine needle aspiration (FNA), where a thin needle withdraws fluid and cells, or a core needle biopsy, which removes a small piece of tissue. A biopsy analyzes the cells to rule out potential malignancy.
Understanding the Implications
A complex cyst diagnosis generally indicates a lesion that requires careful monitoring, though most are found to be benign after investigation. While they need further scrutiny, most complex cysts are non-cancerous. However, a small percentage, ranging from approximately 14% to 23% in some studies, may be malignant or atypical.
Management strategies vary based on the biopsy results and how the cyst appears on imaging. If the biopsy confirms the cyst is benign, observation with follow-up imaging, such as ultrasound, may be recommended every 6 to 12 months for up to two years. If the cyst causes discomfort, aspiration to drain the fluid can provide relief. Surgical removal may be considered for cysts that are persistently symptomatic, continue to recur, or if there are any concerning changes or atypical cells found in the biopsy.