A 45-year-old patient presents with hypertension, hematuria, and flank pain. An MRI scan is performed, and the image provided shows multiple cystic lesions in both kidneys. What is the most likely diagnosis?

Autosomal Dominant Polycystic Kidney Disease (ADPKD)

Chronic kidney disease with cystic degeneration

An 8 years old child suffering from recurrent attacks of polyuria since childhood presents to the pediatrics OPD. On examination, the child has short stature. Vitals and B.P. are normal. S. Creatinine - 6 mg/dL, HCO3 - 16 meq/L, S Na+ - 134 meq/L. On USG, bilateral small kidneys are seen. Diagnosis is:

Medullary cystic kidney disease

Baby born at 30 weeks to an 18-year-old primigravida weighing 2 kg, who died after 48 hours, with Apgar scores of 5 and 8 at 1 and 5 minutes, respectively. On autopsy, bilateral enlarged kidneys with multiple radially arranged cysts were found. Which of the following findings is expected to be associated with this?

Congenital anorectal malformation

Congenital cardiac malformation

A 40-year-old man with a known case of hypertension presented with multiple episodes of hematuria and loin pain. His elder brother passed away due to a stroke at the age of 40. What is the probable diagnosis based on the clinical presentation?

Autosomal dominant polycystic kidney disease

Autosomal recessive polycystic kidney disease

IgA nephropathy is not associated with which of the following?

Gross hematuria concurrent with upper respiratory infection

Immunofluorescence deposits contain IgA and IgG

A 7 year old boy presented with generalized edema. Urine examination revealed marked albuminuria. Serum biochemical examinations showed hypoalbuminemia with hyperlipidemia. Kidney biopsy was undertaken. On light microscopic examination, the kidney appeared normal. Electron microscopic examination is most likely to reveal

Fusion of foot processes of the glomerular epithelial cells

Rarefaction of glomerular basement membrane

Deposition of electron dense material in the basement membrane

Cystic Diseases of the Kidney for INI-CET: High-Yield Pathology Lessons

Polycystic Overview - The Cystic Titans

ADPKD vs ARPKD: Gross, Microscopic, Clinical Features

Feature	ADPKD (Autosomal Dominant)	ARPKD (Autosomal Recessive)
Genetics	PKD1 (85%), PKD2 (15%)	PKHD1 (fibrocystin)
Inheritance	Autosomal Dominant	Autosomal Recessive
Age of Onset	Adults (30-50 yrs)	Perinatal, infancy
Key Features	Massive bilateral cysts, enlarged kidneys, HTN, pain, hematuria, ESRD	Bilateral echogenic kidneys, small cysts (radial), oligohydramnios sequence (severe cases)
Associated	Hepatic cysts, Berry aneurysms (SAH risk), MVP	Congenital hepatic fibrosis (CHF), portal HTN, Caroli syndrome

ADPKD - The Dominant Disruptor

Genetics: Autosomal dominant.
- PKD1 (Chr 16, ~85%): Polycystin-1. More severe, earlier ESRD.
- PKD2 (Chr 4, ~15%): Polycystin-2. Milder, later ESRD.
Pathophysiology: Defective polycystins → ciliary dysfunction → cyst formation.
Clinical Triad: Flank pain, hematuria, palpable kidneys. Hypertension common.
Extra-renal: Liver cysts (>70%), intracranial "berry" aneurysms (5-10%), MVP, colonic diverticula.

⭐ Intracranial berry aneurysms occur in 5-10% of ADPKD patients; rupture is a major cause of subarachnoid hemorrhage and mortality.
Diagnosis (Ultrasound - Ravine modified for +ve family history):
- Age 15-39: ≥ 3 cysts (unilateral/bilateral).
- Age 40-59: ≥ 2 cysts in each kidney.
- Age ≥ 60: ≥ 4 cysts in each kidney.

ARPKD & NPHP/MCKD Complex - Recessive & Medullary Riddles

Autosomal Recessive Polycystic Kidney Disease (ARPKD):
- Gene: PKHD1 (fibrocystin).
- Presentation: Neonatal, Potter sequence.
- Kidneys: Bilateral, enlarged, echogenic; radial cysts.
- Liver: Congenital hepatic fibrosis (CHF), Caroli syndrome.
⭐ Congenital hepatic fibrosis is universally present in ARPKD and can lead to portal hypertension.
NPHP/MCKD Complex: Tubulointerstitial fibrosis, medullary cysts, progression to ESRD.
- Nephronophthisis (NPHP):
  - AR; Childhood/Adolescent ESRD.
  - Kidneys: Normal/small, shrunken later; loss of corticomedullary differentiation (CMD).
  - Associations: Retinitis pigmentosa (Senior-Løken syndrome 📌), hepatic fibrosis, cerebellar ataxia.
- Medullary Cystic Kidney Disease (MCKD):
  - AD (Types 1 & 2); Adult ESRD.
  - Kidneys: Similar to NPHP. UMOD gene (MCKD2).

Other Renal Cysts - Cyst Classification Capers

Simple Cysts: Common, benign, usually asymptomatic.
Complex Cysts (Bosniak Classification): Key for management. 📌 Mnemonic: "One Fine Fellow, Maybe Malignant" (I, II, IIF, III, IV)
- I: Benign simple cyst. Malignancy risk: 0%.
- II: Benign; few thin septa/calcifications. Malignancy risk: 0%.
- IIF: Minimally complex; more septa/thicker calcifications. Requires Follow-up. Malignancy risk: ~5%.
- III: Indeterminate; thick/irregular septa/walls, measurable enhancement. Malignancy risk: ~50%.
- IV: Clearly malignant; enhancing soft tissue components. Malignancy risk: ~100%.
⭐ Bosniak category IV cysts have a nearly 100% risk of malignancy.
Acquired Cystic Kidney Disease (ACKD): Associated with long-term dialysis. Increased risk of RCC.
Medullary Sponge Kidney (MSK): Benign condition. Features medullary duct ectasia, nephrocalcinosis.

Bosniak classification of cystic renal masses

High‑Yield Points - ⚡ Biggest Takeaways

ADPKD: Most common inherited; PKD1 (chr 16) > PKD2; berry aneurysms, hepatic cysts.

ARPKD: PKHD1 (chr 6); infantile presentation, congenital hepatic fibrosis, Potter sequence.

Medullary Sponge Kidney: Benign; papillary collecting duct ectasia; recurrent stones, hematuria.

Nephronophthisis: Major cause of pediatric ESRD; tubulointerstitial fibrosis, corticomedullary cysts.

Acquired Cystic Disease: Develops in ESRD/dialysis patients; increased risk of renal cell carcinoma.

Von Hippel-Lindau: Multiple cysts; high risk of clear cell RCC, hemangioblastomas.

Simple Renal Cysts: Common, usually asymptomatic, benign; smooth, anechoic on ultrasound.

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