Definition/General

Introduction: A phyllodes tumor with osteosarcoma is a malignant phyllodes tumor that contains a component of osteosarcoma as a form of heterologous stromal differentiation.
Origin: The osteosarcoma arises from the stromal component of the phyllodes tumor.
Classification: It is a subtype of malignant phyllodes tumor.
Epidemiology: It is an extremely rare finding.

Clinical Features

Presentation: Presents as a large, rapidly growing, palpable breast mass.
Symptoms: A painless breast lump is the most common symptom.
Risk Factors: Not applicable.
Screening: Mammography and ultrasound show a large, complex mass, which may have calcifications.

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Gross Description

Appearance:
-A large, fleshy mass with areas of necrosis and hemorrhage
-The osteosarcomatous component may appear as a hard, gritty, bony area.
Characteristics: The tumor is often large and infiltrative.
Size Location: Size is variable.
Multifocality: Rare.

Microscopic Description

Histological Features:
-The lesion is a malignant phyllodes tumor with a focus of osteosarcoma
-The osteosarcoma is characterized by the presence of malignant stromal cells producing osteoid or bone.
Cellular Characteristics: The cytological features are those of osteosarcoma.
Architectural Patterns: The background is that of a malignant phyllodes tumor.
Grading Criteria: This is a high-grade lesion.

Immunohistochemistry

Positive Markers: The osteosarcomatous component may be positive for SATB2.
Negative Markers: Not applicable.
Diagnostic Utility: IHC can be used to support the diagnosis.
Molecular Subtypes: Not applicable.

Molecular/Genetic

Genetic Mutations: Not well characterized.
Molecular Markers: No specific molecular markers are routinely used for diagnosis.
Prognostic Significance: The prognosis is very poor.
Therapeutic Targets:
-Treatment is aggressive, involving surgery and often chemotherapy.

Differential Diagnosis

Similar Entities:
-Metaplastic carcinoma with osteosarcomatous differentiation
-Primary breast osteosarcoma.
Distinguishing Features:
-Metaplastic carcinoma has a malignant epithelial component
-Primary breast osteosarcoma lacks an epithelial component.
Diagnostic Challenges: The main challenge is to identify the osteosarcomatous component.
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]