Definition/General
Introduction:
Normal kidney FNAC shows typical renal parenchymal elements
Includes glomerular, tubular, and stromal components
FNAC of normal kidney rare but may be performed for medical renal disease evaluation
Understanding normal cytology essential for interpretation.
Origin:
Sample contains nephrons and supporting structures
Glomerular epithelium and capillaries
Tubular epithelium (proximal and distal)
Interstitial cells and blood vessels
May include urothelial elements.
Classification:
Glomerular elements: visceral and parietal epithelium
Tubular elements: proximal tubules (brush border), distal tubules
Vascular elements: endothelial cells
Interstitial elements: fibroblasts, inflammatory cells.
Epidemiology:
FNAC of normal kidney rarely performed
May be done for transplant evaluation
Medical renal disease assessment
Core biopsy preferred for renal diseases
Normal anatomy knowledge essential for pathologists.
Clinical Features
Presentation:
Usually asymptomatic normal kidney function
Normal serum creatinine
Normal urinalysis
No proteinuria or hematuria
Normal blood pressure
FNAC rarely indicated for normal kidney.
Symptoms:
No specific symptoms in normal kidney
Normal urine output
No flank pain
No urinary symptoms
Normal renal function tests
May be incidental sampling during other procedures.
Risk Factors:
No risk factors for normal kidney
Adequate hydration maintains normal function
Normal blood pressure
No diabetes mellitus
No nephrotoxic medications.
Screening:
No screening needed for normal kidney
Annual check-ups with creatinine
Urinalysis as part of routine care
Blood pressure monitoring
Diabetic patients need regular monitoring.
Master Normal Kidney FNAC Pathology with RxDx
Access 100+ pathology videos and expert guidance with the RxDx app
Gross Description
Appearance:
Normal kidney has smooth capsular surface
Reddish-brown color
Distinct cortex and medulla
Pyramidal medullary structures
Clear corticomedullary junction.
Characteristics:
Firm consistency
Intact capsule
Normal size (10-12 cm length)
Bean-shaped configuration
Hilum with vessels and ureter
No masses or cysts.
Size Location:
Normal size 10-12 cm × 5-6 cm × 3-4 cm
Weight 120-170 grams
Retroperitoneal location
Right kidney slightly lower than left
Normal anatomical relationships.
Multifocality:
Uniform appearance throughout cortex
Regular medullary pyramids
No focal lesions
Symmetric bilateral kidneys
Normal vascular pattern.
Microscopic Description
Histological Features:
Normal glomerular architecture
Tubular epithelium with intact basement membranes
Interstitial stroma minimal
Blood vessels with normal walls
No inflammation or fibrosis.
Cellular Characteristics:
Glomerular epithelial cells: podocytes and parietal cells
Tubular cells: cuboidal with round nuclei
Proximal tubules: brush border, eosinophilic cytoplasm
Distal tubules: clearer cytoplasm, no brush border.
Architectural Patterns:
Normal nephron architecture
Glomerular tufts within Bowman capsule
Tubular lumina patent and regular
Normal collecting duct system
Preserved corticomedullary architecture.
Grading Criteria:
No grading applicable to normal tissue
Normal cellular morphology
Normal architectural relationships
No pathological changes.
Immunohistochemistry
Positive Markers:
PAX2/PAX8 (renal epithelium)
Nephrin (podocytes)
WT1 (podocytes)
Cytokeratin (tubular epithelium)
CD31 (endothelium)
Vimentin (interstitial cells).
Negative Markers:
Tumor markers negative
RCC marker negative
Chromogranin negative
Melanoma markers negative
No pathological markers present.
Diagnostic Utility:
Confirms renal origin of tissue
PAX8 positivity confirms renal epithelium
Normal expression patterns
Helps exclude neoplastic processes
Research applications for renal diseases.
Molecular Subtypes:
No molecular subtypes in normal tissue
Normal gene expression patterns
Baseline for comparison with pathological states
Normal metabolic pathways.
Molecular/Genetic
Genetic Mutations:
No pathological mutations in normal kidney
Normal chromosome complement
Wild-type tumor suppressor genes
Normal oncogene expression
Genetic stability maintained.
Molecular Markers:
Normal protein expression
Normal metabolic enzymes
Appropriate growth factor signaling
Normal cell cycle regulation
Intact DNA repair mechanisms.
Prognostic Significance:
Excellent prognosis with normal kidney function
No progression expected
Normal lifespan anticipated
Maintains homeostasis
Good response to physiological demands.
Therapeutic Targets:
No treatment needed
Maintain normal function
Preventive measures important
Avoid nephrotoxic agents
Regular monitoring in at-risk patients.
Differential Diagnosis
Similar Entities:
Minimal change disease
Early diabetic nephropathy
Hypertensive nephrosclerosis (early)
Acute tubular necrosis (recovery phase)
Drug-induced changes.
Distinguishing Features:
Normal: No pathological changes
Normal: Intact architecture
Disease states: Specific pathological features
Clinical correlation essential
Laboratory values help distinguish.
Diagnostic Challenges:
Early disease states may appear normal
Sampling adequacy important
Processing artifacts may confuse
Clinical correlation mandatory
Serial biopsies may be needed.
Rare Variants:
Normal anatomical variants
Fetal lobulation
Compound calyx
Duplex collecting system
These are normal variants, not pathology.
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
FNAC from kidney, [location]
Adequacy
Specimen is adequate for evaluation
Cellular Findings
Smears show normal renal parenchymal elements
Glomerular Elements
Normal glomerular epithelial cells present
Tubular Elements
Normal tubular epithelium with [proximal/distal] features
Pathological Changes
No pathological changes identified
Inflammation
No significant inflammatory infiltrate
Final Diagnosis
FNAC kidney: Normal renal parenchyma