Complex Sclerosing Lesion

• A Complex Sclerosing Lesion is a benign breast growth that involves a mixture of glandular and connective tissue changes.
• These lesions often present without noticeable symptoms and are typically discovered during routine mammograms.
• Due to their ability to mimic cancerous lesions on imaging, a definitive diagnosis usually requires a biopsy.
• While generally benign, some CSLs, particularly larger ones, may warrant close monitoring or excision.

What is Complex Sclerosing Lesion?

A Complex Sclerosing Lesion refers to a benign proliferation of breast tissue that combines features of sclerosing adenosis, papilloma, and usual ductal hyperplasia. These lesions are characterized by a central fibrous core with entrapped ducts and lobules, leading to a distorted architectural pattern. While they are not cancerous, their complex structure can make them challenging to distinguish from malignant lesions on imaging studies, which is why understanding complex sclerosing lesions is crucial for both patients and clinicians. They are relatively common and are considered a type of benign proliferative breast disease without atypia, meaning they do not typically carry a significantly increased risk of breast cancer on their own, although the presence of other atypical features alongside them can alter risk assessment.

Complex Sclerosing Lesions are often microscopic but can grow larger, sometimes forming a palpable mass. The term “complex” highlights the varied microscopic features, including stromal sclerosis (hardening of connective tissue), epithelial proliferation (growth of cells lining ducts), and adenosis (enlargement of glandular components). These architectural changes can sometimes lead to calcifications or distortions that are visible on mammograms, prompting further investigation. According to studies, these lesions are found in approximately 1-4% of breast biopsies, often incidentally discovered during work-ups for other breast concerns.

Complex Sclerosing Lesion Symptoms

Complex Sclerosing Lesions typically do not cause any specific symptoms that a person would notice on their own. They are most frequently discovered incidentally during routine breast cancer screening, such as mammography. When present, complex sclerosing lesion symptoms are usually subtle or non-existent. However, if a lesion grows to a significant size, it might present as a palpable lump or mass in the breast. It is important to note that even when palpable, these lumps are usually firm and non-tender, similar to many other benign breast conditions.

In some cases, a Complex Sclerosing Lesion might cause architectural distortion or microcalcifications that are only detectable through imaging. These findings are often what prompt further diagnostic steps. Potential findings that might lead to the discovery of a CSL include:

• A new or changing area of architectural distortion on a mammogram.
• Clustered microcalcifications that appear suspicious.
• A palpable mass that is firm and irregular.
• An area of asymmetry or focal density on imaging.

Because these signs are non-specific and can also be associated with malignant conditions, any suspicious finding requires thorough evaluation by a healthcare professional.

Diagnosing Complex Sclerosing Lesions

The process of complex sclerosing lesion diagnosis typically begins with imaging studies, often initiated due to a screening mammogram finding or a palpable lump. Mammography may reveal a stellate lesion (star-shaped), an area of architectural distortion, or clustered microcalcifications that raise suspicion. Ultrasound and magnetic resonance imaging (MRI) may also be used to further characterize the lesion, providing additional details about its size, shape, and blood flow patterns. However, even with advanced imaging, it can be difficult to definitively differentiate a Complex Sclerosing Lesion from certain types of breast cancer, particularly invasive ductal carcinoma.

Therefore, a definitive diagnosis almost always requires a tissue biopsy. This involves removing a small sample of the suspicious tissue for microscopic examination by a pathologist. Common biopsy methods include core needle biopsy, which uses a hollow needle to extract tissue samples, or excisional biopsy, which involves surgically removing the entire lesion. The pathologist’s examination of the tissue is crucial for confirming the benign nature of the lesion and ruling out malignancy. If a Complex Sclerosing Lesion is diagnosed via core needle biopsy, surgical excision may sometimes be recommended, especially if there are any atypical features or if the imaging findings remain discordant with the biopsy results, to ensure no malignancy was missed.