Definition/General
Introduction:
A complex sclerosing lesion (CSL) is a benign proliferative breast lesion that is essentially a large radial scar, typically defined as being 1 cm or larger
It is characterized by a central fibroelastotic core with entrapped glands radiating outwards.
Origin:
Similar to radial scars, the pathogenesis is thought to be related to a localized area of injury and subsequent scarring and proliferation.
Classification:
CSLs are classified as benign proliferative breast lesions without atypia
The term is often used for radial scars >1 cm.
Epidemiology:
They are common incidental findings in breast biopsies and screening mammograms
They are most common in women aged 40-60 years.
Clinical Features
Presentation:
CSLs are typically asymptomatic and are not palpable
They are usually detected on mammography as a spiculated mass or architectural distortion.
Symptoms:
Asymptomatic.
Risk Factors:
There are no well-established risk factors.
Screening:
The mammographic appearance of a CSL is highly suspicious for malignancy, which is why biopsy is almost always performed.
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Gross Description
Appearance:
A firm, gray-white, stellate lesion with a central puckered area
The size is 1 cm or greater.
Characteristics:
The radiating arms can be seen extending into the surrounding fat.
Size Location:
Can occur anywhere in the breast.
Multifocality:
Can be multifocal.
Microscopic Description
Histological Features:
The lesion has a central fibroelastotic core containing entrapped, often distorted, glands
Radiating from the core are ducts and lobules showing various proliferative changes, such as hyperplasia, adenosis, and cysts
A myoepithelial layer is preserved.
Cellular Characteristics:
The epithelial cells are typically bland
The stroma is hyalinized and elastotic.
Architectural Patterns:
The key feature is the stellate architecture with a central scar.
Grading Criteria:
This is a benign lesion.
Immunohistochemistry
Positive Markers:
The myoepithelial cell layer is highlighted by myoepithelial markers such as p63 and calponin.
Negative Markers:
Not typically required for diagnosis.
Diagnostic Utility:
IHC for myoepithelial markers is crucial to differentiate the entrapped glands in a CSL from invasive carcinoma, especially tubular carcinoma.
Molecular Subtypes:
Molecular subtyping is not relevant for this benign condition.
Molecular/Genetic
Genetic Mutations:
This is a benign condition and is not associated with specific genetic mutations.
Molecular Markers:
No specific molecular markers are routinely used for diagnosis.
Prognostic Significance:
CSLs are associated with a small increased risk (about 2 fold) of developing invasive breast cancer
More importantly, they are frequently associated with atypical lesions (ADH, LCIS) and carcinoma (DCIS, invasive).
Therapeutic Targets:
Surgical excision is often recommended when a CSL is diagnosed on core needle biopsy to exclude an associated malignancy.
Differential Diagnosis
Similar Entities:
Invasive ductal carcinoma, especially tubular carcinoma
Sclerosing adenosis.
Distinguishing Features:
Tubular carcinoma lacks a myoepithelial layer and has a different architecture
Sclerosing adenosis is more lobulocentric and lacks the central fibroelastotic core of a CSL.
Diagnostic Challenges:
The main challenge is distinguishing a CSL from tubular carcinoma on a small biopsy
The entrapped glands can be very distorted and mimic invasion
IHC for myoepithelial markers is essential.
Rare Variants:
There are no specific rare variants.
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
[specimen type], measuring [size] cm in greatest dimension
Diagnosis
[diagnosis name]
Classification
Classification: [classification system] [grade/type]
Histological Features
Shows [architectural pattern] with [nuclear features] and [mitotic activity]
Size and Extent
Size: [X] cm, extent: [local/regional/metastatic]
Margins
Margins are [involved/uninvolved] with closest margin [X] mm
Lymphovascular Invasion
Lymphovascular invasion: [present/absent]
Lymph Node Status
Lymph nodes: [X] positive out of [X] examined
Special Studies
IHC: [marker]: [result]
Molecular: [test]: [result]
[other study]: [result]
Final Diagnosis
Final diagnosis: [complete diagnosis]