Definition/General
Introduction:
Columnar cell hyperplasia (CCH) is a benign proliferative breast lesion characterized by more than two layers of columnar epithelial cells lining the terminal duct-lobular units (TDLUs), without cytological atypia
It is part of the spectrum of columnar cell lesions.
Origin:
CCH 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:
CCH is a very common incidental finding, especially in biopsies performed for microcalcifications
It is most common in perimenopausal and postmenopausal women.
Clinical Features
Presentation:
CCH 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:
CCH is often associated with amorphous or punctate microcalcifications on mammography.
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Gross Description
Appearance:
There are no specific gross findings for CCH.
Characteristics:
Gross findings are not specific for this microscopic diagnosis.
Size Location:
Gross findings are not specific for this microscopic diagnosis.
Multifocality:
CCH can be multifocal.
Microscopic Description
Histological Features:
The TDLUs are lined by more than two layers of columnar epithelial cells, which may form tufts or mounds
The cells have oval to elongated nuclei and abundant eosinophilic cytoplasm with apical snouts.
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 multilayering of columnar cells, which can create a hobnail appearance
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 hyperplasia 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 CCH without atypia
Management is focused on the associated lesions, if any.
Differential Diagnosis
Similar Entities:
Flat epithelial atypia (FEA)
Usual ductal hyperplasia (UDH).
Distinguishing Features:
FEA is distinguished by the presence of low-grade cytological atypia
UDH has a more heterogeneous cell population and a different IHC profile (mosaic CK5/6 positivity).
Diagnostic Challenges:
The main challenge is distinguishing CCH 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]