Definition/General
Introduction:
Adenosis is a benign proliferative breast lesion characterized by an increase in the number and size of the acini within the terminal duct-lobular unit (TDLU)
It is a common component of fibrocystic changes.
Origin:
It arises from the TDLU.
Classification:
Adenosis is classified as a benign proliferative breast lesion without atypia
There are several variants, including sclerosing adenosis, tubular adenosis, and microglandular adenosis.
Epidemiology:
It is a very common finding in breast biopsies, especially in the perimenopausal period.
Clinical Features
Presentation:
Adenosis is typically an incidental microscopic finding.
Symptoms:
Asymptomatic.
Risk Factors:
There are no well-established risk factors for adenosis.
Screening:
It can be associated with microcalcifications on mammography.
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Gross Description
Appearance:
There are no specific gross findings.
Characteristics:
Gross findings are not specific for this microscopic diagnosis.
Size Location:
Gross findings are not specific for this microscopic diagnosis.
Multifocality:
Often multifocal.
Microscopic Description
Histological Features:
The lesion is characterized by a lobulocentric proliferation of glands
The number of acini per lobule is increased, and the lobule is enlarged
The glands are lined by a double layer of epithelial and myoepithelial cells.
Cellular Characteristics:
The epithelial and myoepithelial cells are bland, without atypia.
Architectural Patterns:
The key feature is the increased number of glands within a preserved lobular architecture.
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 can be used to confirm the benign nature of the lesion.
Molecular Subtypes:
Molecular subtyping is not relevant for this benign condition.
Molecular/Genetic
Genetic Mutations:
Adenosis 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:
Adenosis without atypia is associated with a small increased risk (about 1.5-2 fold) of developing invasive breast cancer.
Therapeutic Targets:
No treatment is required.
Differential Diagnosis
Similar Entities:
Sclerosing adenosis
Tubular adenosis
Invasive carcinoma.
Distinguishing Features:
Sclerosing adenosis has stromal sclerosis and glandular distortion
Tubular adenosis has more closely packed, uniform tubules
Invasive carcinoma lacks a myoepithelial layer.
Diagnostic Challenges:
The main challenge is to distinguish florid adenosis from invasive carcinoma, especially on a small biopsy.
Rare Variants:
Variants include sclerosing, tubular, microglandular, and apocrine adenosis.
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]