Definition/General
Introduction:
A fibroadenoma with microglandular adenosis (MGA) is a fibroadenoma that contains foci of MGA within its epithelial component.
Origin:
The MGA arises from the epithelial component of the fibroadenoma.
Classification:
It is a subtype of complex fibroadenoma.
Epidemiology:
It is a rare finding.
Clinical Features
Presentation:
Presents as a painless, firm, mobile, well-circumscribed, rubbery mass, similar to a simple fibroadenoma.
Symptoms:
A painless, mobile lump is the most common symptom.
Risk Factors:
There are no well-established risk factors.
Screening:
On mammography, they appear as a well-circumscribed, oval mass.
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Gross Description
Appearance:
A well-circumscribed, encapsulated, firm, gray-white mass.
Characteristics:
The gross appearance is indistinguishable from a simple fibroadenoma.
Size Location:
Size is variable.
Multifocality:
Can be multiple.
Microscopic Description
Histological Features:
The lesion is a fibroadenoma with a focus of MGA
The MGA is characterized by a haphazard proliferation of small, round, open glands, with an absent myoepithelial layer.
Cellular Characteristics:
The cytological features are those of MGA.
Architectural Patterns:
The background is that of a fibroadenoma.
Grading Criteria:
This is a benign lesion.
Immunohistochemistry
Positive Markers:
The MGA component is positive for S100.
Negative Markers:
The MGA component is negative for ER, PR, and myoepithelial markers.
Diagnostic Utility:
IHC is useful to confirm the MGA component.
Molecular Subtypes:
Molecular subtyping is not relevant for this benign condition.
Molecular/Genetic
Genetic Mutations:
Not well characterized.
Molecular Markers:
No specific molecular markers are routinely used for diagnosis.
Prognostic Significance:
A fibroadenoma with MGA is associated with an increased risk of subsequent breast cancer, similar to that of MGA in the absence of a fibroadenoma.
Therapeutic Targets:
No specific treatment is required.
Differential Diagnosis
Similar Entities:
Fibroadenoma with tubular carcinoma.
Distinguishing Features:
Tubular carcinoma is S100-negative and ER-positive.
Diagnostic Challenges:
The main challenge is to distinguish the MGA component from tubular carcinoma.
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]