Definition/General

Introduction:
-Columnar cell change (CCC) is a benign breast lesion characterized by the replacement of the native epithelium of the terminal duct-lobular units (TDLUs) by one or two layers of columnar epithelial cells
-It is part of a spectrum of columnar cell lesions.
Origin:
-CCC arises from the TDLU
-It is a common finding in breast biopsies.
Classification:
-Columnar cell lesions are classified into columnar cell change (without atypia) and columnar cell hyperplasia (without atypia)
-When atypia is present, it is classified as flat epithelial atypia (FEA).
Epidemiology:
-CCC is a very common incidental finding, especially in biopsies performed for microcalcifications
-It is most common in perimenopausal and postmenopausal women.

Clinical Features

Presentation:
-CCC is asymptomatic and is not associated with a palpable mass
-It is a mammographic finding.
Symptoms: Asymptomatic.
Risk Factors: There are no well-established risk factors.
Screening: CCC is often associated with amorphous or punctate microcalcifications on mammography.

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Gross Description

Appearance: There are no specific gross findings for CCC.
Characteristics: Gross findings are not specific for this microscopic diagnosis.
Size Location: Gross findings are not specific for this microscopic diagnosis.
Multifocality: CCC can be multifocal.

Microscopic Description

Histological Features:
-The TDLUs are lined by one or two layers of columnar cells
-The cells have oval to elongated nuclei, oriented perpendicular to the basement membrane
-The cytoplasm is abundant and eosinophilic
-Apical snouts are prominent.
Cellular Characteristics:
-The cells show no significant cytological atypia
-The nuclei are uniform and normochromatic
-Mitotic activity is absent or very low.
Architectural Patterns:
-The key feature is the replacement of the normal cuboidal epithelium by columnar cells
-The acini are often dilated.
Grading Criteria: This is a benign lesion.

Immunohistochemistry

Positive Markers:
-The cells are strongly and diffusely positive for ER
-They are positive for low molecular weight cytokeratins.
Negative Markers: They are negative for high molecular weight cytokeratins.
Diagnostic Utility: IHC is not usually necessary for the diagnosis.
Molecular Subtypes: Molecular subtyping is not relevant for this benign condition.

Molecular/Genetic

Genetic Mutations:
-Columnar cell lesions can show some genetic alterations, such as loss of heterozygosity at 16q, which are also seen in FEA and low-grade DCIS.
Molecular Markers: No specific molecular markers are routinely used for diagnosis.
Prognostic Significance:
-Columnar cell change without atypia is considered a low-risk lesion
-Its main significance is its association with FEA, DCIS, and invasive carcinoma.
Therapeutic Targets:
-No specific treatment is required for CCC without atypia
-Management is focused on the associated lesions, if any.

Differential Diagnosis

Similar Entities:
-Flat epithelial atypia (FEA)
-Apocrine metaplasia.
Distinguishing Features:
-FEA is distinguished by the presence of low-grade cytological atypia
-Apocrine metaplasia has cells with more abundant, granular, eosinophilic cytoplasm and prominent nucleoli.
Diagnostic Challenges: The main challenge is distinguishing CCC without atypia from FEA, which relies on the subjective assessment of cytological atypia.
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]