Definition/General

Introduction:
-Carcinoma arising within a phyllodes tumor is a rare event
-The carcinoma can be in situ or invasive, and of ductal or lobular type
-It arises from the epithelial component of the phyllodes tumor.
Origin: The carcinoma arises from the epithelial component of the phyllodes tumor.
Classification:
-The phyllodes tumor is graded as benign, borderline, or malignant based on its stromal features
-The carcinoma is classified and graded separately.
Epidemiology:
-It is a rare finding, seen in a small percentage of phyllodes tumors.

Clinical Features

Presentation: Presents as a palpable breast mass.
Symptoms: A painless breast lump is the most common symptom.
Risk Factors: Not applicable.
Screening: Mammography and ultrasound show a well-circumscribed mass.

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Gross Description

Appearance:
-A large, well-circumscribed, lobulated mass.
Characteristics: The gross appearance is indistinguishable from a phyllodes tumor without carcinoma.
Size Location: Size is variable.
Multifocality: Rare.

Microscopic Description

Histological Features:
-The lesion is a phyllodes tumor with a focus of carcinoma (in situ or invasive)
-The carcinoma is confined to the epithelial component of the phyllodes tumor.
Cellular Characteristics: The cytological features are those of the specific type of carcinoma.
Architectural Patterns: The background is that of a phyllodes tumor.
Grading Criteria: The phyllodes tumor and the carcinoma are graded separately.

Immunohistochemistry

Positive Markers: The IHC profile is that of the specific carcinoma type.
Negative Markers: Not applicable.
Diagnostic Utility:
-IHC is used to classify the carcinoma and to determine ER, PR, and HER2 status.
Molecular Subtypes: The molecular subtype is that of the carcinoma.

Molecular/Genetic

Genetic Mutations: The genetic alterations are those of the specific carcinoma type.
Molecular Markers: Not applicable.
Prognostic Significance:
-The prognosis is determined by the stromal grade of the phyllodes tumor and the characteristics of the carcinoma (type, grade, and presence of invasion).
Therapeutic Targets: Treatment is based on the characteristics of both the phyllodes tumor and the carcinoma.

Differential Diagnosis

Similar Entities:
-Phyllodes tumor with atypia
-Metaplastic carcinoma.
Distinguishing Features:
-The distinction between atypia and carcinoma in situ is based on standard criteria
-Metaplastic carcinoma has a malignant stromal component that is thought to be derived from the carcinoma.
Diagnostic Challenges: The main challenge is to identify the carcinoma within the phyllodes tumor.
Rare Variants: Not applicable.

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]

Prognostic Factors

Prognostic factors: [list factors]

Final Diagnosis

Final diagnosis: [complete diagnosis]