Definition/General
Introduction:
Phyllodes tumor with tubular carcinoma is an extremely rare malignant phyllodes tumor where the stromal component contains tubular carcinoma characterized by well-formed tubular structures with open lumina.
Origin:
Develops from intralobular breast stroma with differentiation toward tubular carcinoma
May arise through specific glandular differentiation of stromal cells forming characteristic tubular architecture.
Classification:
WHO Classification categorizes this as malignant phyllodes tumor with heterologous elements
Tubular carcinoma component shows well-differentiated tubular structures.
Epidemiology:
Exceptionally rare with fewer than 5 cases reported worldwide
Peak age 50-70 years
Female predominance
Generally associated with better prognosis than other heterologous types.
Clinical Features
Presentation:
Large, slowly growing breast mass
Usually presents as well-circumscribed mass
May show gradual enlargement over years
Often clinically benign appearance.
Symptoms:
Progressive but slow breast enlargement
Usually completely asymptomatic
May be discovered on routine screening
Breast asymmetry
No constitutional symptoms.
Risk Factors:
Previous phyllodes tumor history
Older age
Family history of breast cancer
Hormonal factors possible
Screening-detected lesions.
Screening:
Often detected on mammographic screening
Clinical examination may not detect malignancy
Mammography shows spiculated mass
Core needle biopsy essential.
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Gross Description
Appearance:
Large, well-circumscribed to spiculated mass
Cut surface shows gray-white areas with stellate pattern
Firm consistency typical.
Characteristics:
Size typically >3 cm (range 2-8 cm)
Firm consistency
May have spiculated borders
Stellate or radial pattern
No obvious necrosis.
Size Location:
Can occur in any breast region
Usually involves moderate breast tissue
Unilateral presentation
Well-defined but may have irregular borders.
Multifocality:
Typically unifocal mass
Tubular areas may be multifocal within tumor
Radial growth pattern
Local extension through tubular structures.
Microscopic Description
Histological Features:
Biphasic tumor with epithelial and mesenchymal components
Tubular carcinoma areas show well-formed tubular structures with open lumina lined by single layer of epithelial cells.
Cellular Characteristics:
Small, well-differentiated epithelial cells
Low nuclear grade
Minimal mitotic activity
Single cell layer lining tubules
Apical snouts may be present.
Architectural Patterns:
Well-formed tubular structures with open lumina
Tubules arranged in haphazard pattern
Desmoplastic stroma surrounding tubules
>90% tubular architecture required.
Grading Criteria:
Low nuclear grade (Grade 1)
Low mitotic rate (<10 per 10 HPF)
Well-differentiated tubular architecture
Minimal pleomorphism.
Immunohistochemistry
Positive Markers:
Estrogen receptor strongly positive (>90%)
Progesterone receptor positive
Cytokeratins positive (CK7, CK8/18)
EMA positive
Epithelial component: CK7+, EMA+.
Negative Markers:
HER2 negative
CK5/6 negative
EGFR negative
p53 usually normal pattern
Myoepithelial markers negative.
Diagnostic Utility:
Strong hormone receptor positivity characteristic
Luminal A-type immunoprofile
Low Ki-67 index typical
Absence of myoepithelial markers confirms invasion.
Molecular Subtypes:
Luminal A subtype
Hormone receptor-positive, HER2-negative
Low-grade, well-differentiated type.
Molecular/Genetic
Genetic Mutations:
PIK3CA mutations common
CDH1 mutations possible
Low tumor mutational burden
TP53 mutations rare.
Molecular Markers:
Luminal A gene expression profile
High hormone receptor expression
Low proliferation signature
Low Ki-67 index (<20%).
Prognostic Significance:
Excellent prognosis similar to pure tubular carcinoma
Hormone receptor positivity predicts excellent response to endocrine therapy
Low recurrence rate.
Therapeutic Targets:
Endocrine therapy (tamoxifen, aromatase inhibitors)
CDK4/6 inhibitors for advanced disease
Excellent response to hormonal manipulation.
Differential Diagnosis
Similar Entities:
Pure tubular carcinoma of breast
Tubular adenosis
Microglandular adenosis
Invasive ductal carcinoma with tubular features
Complex sclerosing lesion.
Distinguishing Features:
Phyllodes with tubular: Leaf-like areas, >90% tubular
Adenosis: Myoepithelial cells present
Complex sclerosing lesion: Radial scar, no invasion.
Diagnostic Challenges:
Recognition of tubular features
Distinction from benign tubular lesions
Assessment of invasion vs adenosis
Quantification of tubular component.
Rare Variants:
Tubular carcinoma with cribriform features
Mixed tubular and ductal carcinoma
Tubular carcinoma with lobular features.
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]