Definition/General

Introduction:
-A radial scar is a benign proliferative breast lesion characterized by a central fibroelastotic core with entrapped glands radiating outwards
-Lesions larger than 1 cm are often called complex sclerosing lesions
-They can mimic invasive carcinoma mammographically.
Origin:
-The exact pathogenesis is unknown, but they are thought to result from a localized area of injury and subsequent scarring and proliferation.
Classification:
-Radial scars are classified as benign proliferative breast lesions without atypia
-However, they are often associated with atypical lesions and carcinoma.
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:
-Radial scars are typically asymptomatic and are not palpable
-They are usually detected on mammography as a spiculated mass or architectural distortion.
Symptoms: Asymptomatic.
Risk Factors: Not applicable.
Screening: The mammographic appearance of a radial scar 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.
Characteristics:
-The size is typically less than 1 cm
-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 applicable.
Diagnostic Utility:
-IHC for myoepithelial markers is crucial to differentiate the entrapped glands in a radial scar from invasive carcinoma, especially tubular carcinoma.
Molecular Subtypes: Not applicable.

Molecular/Genetic

Genetic Mutations: Not applicable.
Molecular Markers: No specific molecular markers are routinely used for diagnosis.
Prognostic Significance:
-Radial scars 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 radial scar 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 radial scar.
Diagnostic Challenges:
-The main challenge is distinguishing a radial scar 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: Not applicable.

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]