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Disease	Inherited?	Renal Findings	Non-renal Findings	Treatment
ARPKD	Yes (chromosome 6)	Large homogenous echogenic kidneys	Hepatic fibrosis Biliary dysgenesis	Respiratory support May require nephrectomy due to compression Splenorenal shunt for portal HTN
ADPKD	Yes PKD1: 16 PKD2: 4 PKD3: not mapped	Cysts throughout renal parenchyma	Diverticulitis Liver/spleen/pancreas cysts Mitral valve prolapse Intracranial aneurysms Seminal vesicle cysts (40%)	Control HTN (ACE/ARB) Consider cyst drainage
Juvenile nephronophthisis Medullary cystic kidney disease	Yes (chromosome 2)	Corticomedullary junction cysts	Retinitis pigmentosa (16%) Hepatic fibrosis	Sodium repletion
Tuberous sclerosis	Yes TSC1: 9 TSC2: 16	Cysts + AMLs RCC (3%)	Epilepsy (80%) Facial angiofibromata (75%) Developmental delay (60%)	Consider AML removal if > 4cm
VHL	Yes (chromosome 3)	Cysts (76%) + adenomas RCC (35-38%)	Cerebellar hemangioblastomas Retinal angiomas Pheochromocytomas (10-17%) Pancreas/epididymis cysts	Partial nephrectomy for cancer control Conisder bilateral nephrectomy
Multicystic dysplastic kidney	No	Minimal nephron development Diffuse cysts		Nephrectomy for pain/hemorrhage
Benign multilocular cyst	No	Normal kidney compromised by growing cystic mass		Partial/radical nephrectomy
Simple cyst	No	Single/multiple cysts More common with increasing age		Depends on Bosniak classification
Medullary sponge kidney	No	Ectatic collecting ducts Normal nephrons		KCit for stones Abx ppx for recurrent UTIs
Acquired renal cystic disease	No	Diffuse cysts Occurs with ESRD		Excision if mass > 3cm

Autosomal Dominant Polycystic Kidney Disease (ADPKD)

• Hematuria presenting sign in 19-35%
• Stones develop in 20-30%
• EPO levels increased, anemia is unusual
• HTN present in 50% 20-35yo, 100% with ESRD
• Intracranial aneurysm present in 10-30%, will cause subarachnoid hemorrhage (sudden severe headache) -> death in 9% of this subgroup, prevent by treating HTN
• Obtain family hx (3 generations) - assess renal disease, HTN, and strokes
• US diagnostic criteria (if family risk): 2+ cysts if < 30yo, 2 cysts per kidney if 30-59yo, and 4 cysts per kidney if > 60yo
• If no family history, diagnose based on bilateral renal cysts and 2+ associated findings: bilateral renal enlargement, 3+ hepatic cysts, cerebral artery aneurysm, solitary cyst of arachnoid/pineal/pancreas/spleen
• Cyst infection: treat with lipophilic antibiotics (bactrim, quinolones, chloramphenicol)
• Aneurysm screening recommendations: family hx aneurysm or SAH, prior naeurysm rupture, preop for major elective surgery, high-risk occupation, or high anxiety regarding potential aneurysm
• Aneurysm management: conservative therapy if < 7mm, otherwise treat (2% risk rupture per year)

Autosomal Recessive Polycystic Kidney Disease (ARPKD)

• Usually apparent at birth, if not will become apparent by age 13-20
• 50% die after birth, another 25% by 1yo
• All patients have hepatic fibrosis and biliary ectasia
• Increased echogenicity on renal US due to microcysts

Juvenile Nephronophthisis (NPH) and Medullary Cystic Kidney Disease (MCKD) Complex

• Similarities: cause polydipsia/polyuria, histologic triad (irregular basement membrane thickening/disintegration, tubular atrophy, interstitial fibrosis)
• Juvenile NPH: autosomal recesive, no HTN, renal failure by 25yo, extrarenal symptoms
• MCKD: autosomal dominant, HTN, renal failure by 50yo

Tuberous Sclerosis

• Diagnosis: 2 major features or 1 major + 2 minor
• Major features: renal AML, facial angiofibromas, ungual/periungual fibromas, 3+ hypomelanotic macules, shagreen patch, multiple retinal hamartomas, cortical tuber, subependymal nodule, subependymal giant cell astrocytoma, cardiac rhabdomyoma, lymphangioleiomyomatosis
• Minor features: multiple renal cysts, nonrenal hamartoma, hamartomatous rectal polyp, retinal achromic patch, cerebral white matter radial migration tracts, bone cysts, gingival fibromas, enamel pits, "confetti" skin lesions
• Renal AML seen in 40-80%, common after 10yo
• Renal cysts in 20%, usually appear by 3yo
• AML management: embolize or excise if > 4cm to prevent spontaneous hemorrhage, otherwise screen with annual renal US or CT
• Surgical indications: > 4cm, pain, bleeding, compromising renal function, concern for RCC
• EXIST-2 trial: patients with TSC or LAM and AML 3+cm, treated with everolimus 10mg daily vs placebo, 4% AML progression (vs 21%), 50% reduction in size in 42% (vs 0%), improvement in skin lesions (26% vs 0%), but risk of stomatitis and acne-lesions

Von Hippel-Lindau (VHL)

• If family history, diagnosis made based on presence of hemangioblastoma, RCC, or PCC
• If no family history, need 2+ "cardinal" manifestations
• Consider partial nephrectomy vs bilateral nephrectomy for cancer control

Multicystic Dysplastic Kidney (MCDK)

• Multiple cysts of different sizes without normal parenchyma and no renal function
• Second most common cause of newborn abdominal mass (after hydronephrosis), most common cause of renal cystic disease
• Atretic ureter and hypoplastic renal vessels
• Contralateral abnormalities: UPJO (3-12%), VUR (18-43%)
• 40% will spontaneously involute
• No association with HTN or neoplasms
• Usually diagnosed on prenatal US and confirmed after birth, cysts are different sizes and no communication (UPJO shows similar sized cysts/calyces with some connectoin)
• DMSA/MAG3: MCDK shows minimal/no function, hydronephrotic kidney will show some function
• Surveillance: some recommend annual BP check, screening renal US at 1yr and 6yr, consider nephrectomy if HTN develops or kidney enlarging

Medullary Sponge Kidney (MSK)

• Distal ductal dilation and diverticula, confined to medullary pyramids
• CT urogram or IVP are best for diagnosis: enlarged kidneys, papillary calficiations, elongated tubules filling with contrast, papillary contrast blush with persistent medullary opacification
• Usually asymptomatic, may present with colic, UTI, or hematuria
• Differentiate from ADPKD - no liver cysts, no cortical cysts, no family history
• Medullary nephrocalcinosis may be present, but differentiate from other causes based on difference in collecting duct caliber (normal vs dilated)
• Potassium citrate often used for hypercalciuria and hypocitraturia
• May require antibiotic prophylaxis if recurrent infections

Benign multilocular cyst (Cystic nephroma)

• Benign end of spectrum ending with cystic Wilms tumor (children) or cystic RCC (adults)
• Usually diagnosed before 4yo (2:1 M:F) or after 30yo (1:8 M:F)
• Asymptomatic flank mass in children, flank mass with pain/hematuria in adults
• Will have compressed normal parenchyma, MCDK has no normal parenchyma

Acquired Renal Cystic Disease

• 3+ cysts in each kidney in ESRD patient, seen with both HD and PD, likely caused by uremia
• RCC: 3x more likely if cysts present, 6x more likely in large vs small cystic kidneys
• If uremic + febrile, consider cyst infection - may require percutaneous drainage
• Persistent bleeding/pain: embolization or nephrectomy
• If HD for 3+yrs, screen with US q6mo if no cysts/tumors or CT+US q6mo if cysts/tumors < 2cm identified
• If tumor > 3cm, recommend surgical removal

Congenital nephrosis

• Similarities: proximal tubule dilation, severe proteinuria
• Finnish type: autosomal recessive, proteinuria present at first UA, 50% mortality by 6mo, (100% by 4yo), treated with transplant
• Diffuse mesangial sclerosis (DMS): 100% ESRD by 3yo, 1/3 associated with Denys-Drash syndrome (nephrotic syndrome, Wilms tumor, +/- DSD)

Other diseases

• Cortical microcystic disease: stable/progressive renal failure, small/normal kidneys with irregular cayces and papillae, family history, glomerular cysts
• Calyceal diverticulum (pyelogenic cyst): outpouching of collecting system, can develop stones
• Parapelvic cyst: parenchymal cyst impinging on renal pelvis, usually asymptomatic and diagnosed incidentally
• Renal sinus cyst: arises from lymphatics or adipose, not renal parenchyma