Definition/General

Introduction:
-Villoglandular adenocarcinoma of the breast is an extremely rare variant of adenocarcinoma characterized by a papillary and glandular architecture
-It is considered a well-differentiated, low-grade malignancy with a favorable prognosis
-It is more commonly described in the cervix and endometrium.
Origin: It is thought to arise from the ductal epithelium of the breast.
Classification: It is a rare variant of invasive ductal carcinoma with papillary features.
Epidemiology:
-Extremely rare, with only a few case reports in the literature
-It typically affects postmenopausal women.

Clinical Features

Presentation:
-Presents as a palpable breast mass
-The clinical and radiological features are non-specific.
Symptoms: A painless breast lump is the most common symptom.
Risk Factors: The risk factors are similar to those for conventional breast cancer.
Screening:
-Usually diagnosed after investigation of a palpable mass
-Mammographic and ultrasound findings are non-specific.

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Gross Description

Appearance:
-A well-circumscribed, soft to firm mass.
Characteristics:
-Size is variable
-The cut surface may appear granular or papillary.
Size Location: Can occur anywhere in the breast.
Multifocality: Rare.

Microscopic Description

Histological Features:
-The tumor is characterized by long, slender papillae lined by stratified, non-squamous epithelium
-The papillae have a central fibrovascular core
-The base of the tumor shows a glandular, infiltrative pattern.
Cellular Characteristics:
-The tumor cells are typically low-grade, with minimal nuclear atypia and low mitotic activity.
Architectural Patterns: A mixture of papillary and glandular patterns is characteristic.
Grading Criteria: These are typically low-grade (Grade 1) tumors.

Immunohistochemistry

Positive Markers:
-The tumor cells are positive for cytokeratins (e.g., CK7)
-They are typically ER and PR positive.
Negative Markers:
-HER2 is usually negative
-Myoepithelial markers are absent in the invasive component.
Diagnostic Utility: IHC is used to support the diagnosis and to determine hormone receptor status.
Molecular Subtypes: Most are of the Luminal A molecular subtype.

Molecular/Genetic

Genetic Mutations: The molecular genetics are not well characterized due to its rarity.
Molecular Markers: No specific molecular markers are routinely used for diagnosis.
Prognostic Significance:
-The prognosis is generally excellent, with a low risk of recurrence and metastasis.
Therapeutic Targets:
-Treatment is primarily surgical
-Endocrine therapy is often used due to the high rate of ER positivity.

Differential Diagnosis

Similar Entities:
-Papillary carcinoma (intraductal or invasive)
-Adenoma of the nipple.
Distinguishing Features:
-Other papillary carcinomas of the breast typically have more complex architecture and higher-grade cytology
-Adenoma of the nipple is a benign lesion confined to the nipple.
Diagnostic Challenges: The main challenge is its rarity and distinguishing it from other papillary lesions of the breast.
Rare Variants: The entire entity is a rare variant.

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]