Definition/General
Introduction:
Invasive papillary carcinoma is a rare variant of invasive ductal carcinoma characterized by a predominantly papillary architecture
It is important to distinguish it from other papillary lesions of the breast.
Origin:
It arises from the ductal epithelium.
Classification:
It is a subtype of invasive ductal carcinoma.
Epidemiology:
It is rare, accounting for less than 1% of all invasive breast cancers
It typically affects postmenopausal women.
Clinical Features
Presentation:
Presents as a palpable, well-circumscribed mass
Nipple discharge can occur.
Symptoms:
A painless breast lump is the most common symptom.
Risk Factors:
The risk factors are similar to those for other types of breast cancer.
Screening:
Mammography shows a well-defined, round or lobulated mass.
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Gross Description
Appearance:
A well-circumscribed, soft, friable mass
It may be cystic.
Characteristics:
The size is variable.
Size Location:
Usually located in the central part of the breast.
Multifocality:
Usually unifocal.
Microscopic Description
Histological Features:
The tumor is composed of papillae with fibrovascular cores that are lined by malignant epithelial cells
The key feature is stromal invasion by the papillary structures or by individual cells
The myoepithelial layer is absent in the invasive component.
Cellular Characteristics:
The cells are typically low to intermediate grade, with mild to moderate nuclear atypia.
Architectural Patterns:
A complex, branching papillary architecture with stromal invasion is characteristic.
Grading Criteria:
Graded using the Nottingham grading system.
Immunohistochemistry
Positive Markers:
The epithelial cells are positive for cytokeratins and are usually ER-positive.
Negative Markers:
The key finding is the absence of myoepithelial markers (e.g., p63, calponin) in the invasive component
HER2 is usually negative.
Diagnostic Utility:
IHC for myoepithelial markers is essential to confirm invasion.
Molecular Subtypes:
Most are of the luminal subtype.
Molecular/Genetic
Genetic Mutations:
Not well characterized.
Molecular Markers:
No specific molecular markers are routinely used for diagnosis.
Prognostic Significance:
The prognosis is generally better than that of adenocarcinoma NST of similar size and grade
Lymph node metastasis can occur.
Therapeutic Targets:
Treatment is similar to that of conventional breast cancer, based on ER and HER2 status.
Differential Diagnosis
Similar Entities:
Encapsulated papillary carcinoma
Papillary DCIS.
Distinguishing Features:
Encapsulated papillary carcinoma is confined by a fibrous capsule
Papillary DCIS is an in situ lesion confined to ducts.
Diagnostic Challenges:
The main challenge is to identify stromal invasion, which can be subtle.
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]