Definition/General

Introduction: A fibroadenoma with atypia is a fibroadenoma that contains foci of atypical ductal hyperplasia (ADH) or atypical lobular hyperplasia (ALH) within its epithelial component.
Origin: The atypia arises within the epithelial component of the fibroadenoma.
Classification: It is a subtype of complex fibroadenoma.
Epidemiology: Atypia is found in a small percentage of fibroadenomas.

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 foci of ADH or ALH
-The atypical proliferation is confined to the epithelial component of the fibroadenoma.
Cellular Characteristics:
-The atypical cells show features of ADH (monotonous proliferation, cribriform patterns) or ALH (discohesive cells, loss of E-cadherin).
Architectural Patterns: The background is that of a fibroadenoma.
Grading Criteria:
-This is a benign lesion, but the presence of atypia is a significant finding.

Immunohistochemistry

Positive Markers: The IHC profile of the atypical component is similar to that of ADH or ALH.
Negative Markers: Not typically required for diagnosis.
Diagnostic Utility: IHC for E-cadherin can be used to distinguish between ductal and lobular atypia.
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 atypia is associated with an increased risk of subsequent breast cancer, similar to that of ADH or ALH in the absence of a fibroadenoma.
Therapeutic Targets: Management may involve surgical excision to ensure the atypical focus is completely removed and to rule out an associated carcinoma.

Differential Diagnosis

Similar Entities:
-Fibroadenoma with DCIS or LCIS
-Phyllodes tumor.
Distinguishing Features: The distinction between atypia and carcinoma in situ within a fibroadenoma is based on the same criteria used for these lesions in the native breast tissue.
Diagnostic Challenges: The main challenge is to identify the focal atypia within the fibroadenoma.
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]