Definition/General
Introduction:
Collecting duct carcinoma is a rare, aggressive subtype of renal cell carcinoma
Represents <1% of all RCCs
Arises from collecting ducts of Bellini
Shows poor prognosis
Also called Bellini duct carcinoma.
Origin:
Originates from epithelium of collecting ducts
Located in renal medulla
Shows high-grade features
Associated with complex genetic alterations
Develops from distal nephron.
Classification:
WHO 2022: Collecting duct carcinoma
Single entity with aggressive behavior
High-grade by definition
Medullary location characteristic
Poor differentiation.
Epidemiology:
Peak incidence 5th-6th decades
Male predominance (2:1)
Very rare (<1% of RCC)
Aggressive clinical course
Poor survival rates.
Clinical Features
Presentation:
Flank pain
Gross hematuria
Palpable mass
Weight loss
Advanced stage at presentation
Metastases often present.
Symptoms:
Abdominal/flank pain
Hematuria
Constitutional symptoms
Back pain
Fatigue
Anemia
Cachexia.
Risk Factors:
No specific risk factors identified
Possible genetic predisposition
No association with common RCC risk factors
Sporadic occurrence.
Screening:
CT/MRI imaging
Medullary location suspicious
Irregular margins
Heterogeneous enhancement
Staging workup essential.
Master CDC Pathology with RxDx
Access 100+ pathology videos and expert guidance with the RxDx app
Gross Description
Appearance:
Medullary location
Gray-white, firm mass
Infiltrative margins
Extensive necrosis
Hemorrhage common
Involves renal sinus.
Characteristics:
Poorly circumscribed
Firm consistency
Gritty texture
Central/medullary location
Invasion of surrounding structures
Necrotic areas.
Size Location:
Medullary/central location
Variable size (3-15 cm)
Involves renal pelvis
Perirenal extension
Renal vein invasion
Lymph node metastases.
Multifocality:
Usually solitary
Extensive local invasion
Early metastases
Retroperitoneal spread
Distant metastases common.
Microscopic Description
Histological Features:
High-grade adenocarcinoma
Tubular and papillary patterns
Desmoplastic stroma
Marked nuclear atypia
High mitotic rate
Extensive necrosis.
Cellular Characteristics:
Pleomorphic cells
High nuclear grade
Prominent nucleoli
Abundant eosinophilic cytoplasm
Atypical mitoses
Multinucleated giant cells.
Architectural Patterns:
Tubular architecture predominant
Papillary areas
Solid sheets
Cribriform pattern
Sarcomatoid differentiation
Desmoplastic reaction.
Grading Criteria:
High-grade by definition
WHO/ISUP Grade 3-4
Marked nuclear pleomorphism
High mitotic activity
Necrosis common.
Immunohistochemistry
Positive Markers:
CK7 - positive
CK19 - positive
CK8/18 - positive
EMA - positive
PAX8 - positive
Ulex europaeus - positive
PNA lectin - positive.
Negative Markers:
CD10 - negative
RCC marker - negative
CA9 - negative
AMACR - negative
CK20 - negative
PSA - negative.
Diagnostic Utility:
CK7 positivity supports diagnosis
Ulex europaeus relatively specific
Negative CD10/RCC helps exclude other RCC
PAX8 confirms renal origin
High molecular weight cytokeratins positive.
Molecular Subtypes:
All cases: CK7+, high-grade features
Distal nephron markers positive
Proximal tubule markers negative
Collecting duct differentiation.
Molecular/Genetic
Genetic Mutations:
Complex genetic alterations
TP53 mutations common
CDKN2A deletions
NF2 mutations
SETD2 mutations
High mutational burden.
Molecular Markers:
p53 pathway disruption
Cell cycle dysregulation
DNA repair defects
Chromosomal instability
High proliferation markers.
Prognostic Significance:
Very poor prognosis
Median survival <2 years
High metastatic rate
Resistance to standard therapies
Stage at presentation critical.
Therapeutic Targets:
Platinum-based chemotherapy
Immunotherapy (anti-PD-1/PD-L1)
Targeted therapy limited
Clinical trials recommended
Aggressive multimodal treatment.
Differential Diagnosis
Similar Entities:
High-grade urothelial carcinoma
Papillary RCC Type 2
Renal medullary carcinoma
Metastatic adenocarcinoma
Sarcomatoid RCC.
Distinguishing Features:
CDC: CK7+, medullary location
Urothelial: CK20+, uroplakin+
Papillary RCC: Better differentiation, AMACR+
Medullary carcinoma: Sickle cell trait, younger age
Metastatic: Organ-specific markers.
Diagnostic Challenges:
Medullary carcinoma vs CDC
High-grade urothelial carcinoma
Sarcomatoid transformation
Limited biopsy material
Extensive necrosis.
Rare Variants:
CDC with sarcomatoid features
CDC with rhabdoid features
Mixed CDC and conventional RCC.
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
Radical nephrectomy specimen with tumor in medullary location
Tumor Description
High-grade carcinoma measuring [X] cm in medullary/central location
Microscopic Features
High-grade adenocarcinoma with tubular architecture, desmoplastic stroma, and marked nuclear atypia
Nuclear Grade
WHO/ISUP Nuclear Grade 4 (high-grade by definition)
pT Stage
pT[stage] - [staging details]
Margins
Surgical margins: [status]
Immunohistochemistry
CK7: Positive, PAX8: Positive, CD10: Negative, RCC: Negative
Final Diagnosis
Collecting duct carcinoma (Bellini duct carcinoma), WHO/ISUP Grade 4, pT[stage]