ADPKD is Highly Likely in This Case
Yes, autosomal dominant polycystic kidney disease (ADPKD) is a strong diagnostic possibility in a 42-year-old man with bilateral multiple renal cysts on CT imaging. 1
Diagnostic Criteria Support ADPKD
For a patient aged 40-59 years, the presence of ≥2 cysts in each kidney on imaging confirms the diagnosis of ADPKD when family history is positive. 2 Even without known family history, bilateral multiple cysts at this age strongly suggest a genetic etiology rather than simple cysts, which are uncommon in adults with this presentation. 3
Age-Specific Imaging Thresholds
The diagnostic criteria for this 42-year-old patient are:
- ≥2 cysts in each kidney confirms ADPKD 2
- ≤2 total cysts would exclude it 2
- If CT shows >10 total cysts, this provides even stronger confirmation 2
Critical Diagnostic Considerations
Family History May Be Misleading
Do not exclude ADPKD based solely on negative family history, as 10-25% of cases arise from de novo mutations. 4 Additionally, PKD2 mutations (15% of cases) cause milder disease with kidney failure typically in the 70s, meaning affected parents may not yet have been diagnosed. 1, 2
Genetic Testing Indications
Genetic testing for PKD1 and PKD2 should be performed when:
- Family history is unknown or negative 1
- Imaging findings are equivocal 1
- Few cysts are present relative to age 3
- Prognostic information is needed for disease management 1
PKD1 mutations (78% of cases) cause more severe disease with kidney failure around age 58-62 years, while PKD2 mutations (15% of cases) result in kidney failure around age 70 years. 2, 4
Differential Diagnosis to Consider
While ADPKD is most likely, other genetic causes of bilateral renal cysts include:
- HNF1B-related kidney disease (up to 50% are de novo cases) 2
- Tuberous sclerosis complex (TSC1/TSC2 mutations) 2
- Von Hippel-Lindau syndrome (VHL mutations) 2
- Autosomal recessive PKD (though 3% of ADPKD can present with very early onset mimicking ARPKD) 2
Acquired cystic disease (ACD) occurs exclusively in end-stage renal disease or dialysis patients, so this would be excluded if kidney function is preserved. 1, 2
Next Steps for Confirmation
Imaging Optimization
If the CT findings are atypical or equivocal, contrast-enhanced MRI provides superior anatomic detail and higher sensitivity for small cysts. 3 MRI criteria for ages 16-40 years (>10 total cysts confirms, <5 excludes) can provide additional diagnostic clarity. 2
Assess for Extrarenal Manifestations
Look for features that support ADPKD:
- Liver cysts (present in >80% by age 30, nearly universal by age 42) 1, 4
- Hypertension (affects 70-80% of patients) 4
- History of gross hematuria or flank pain 5
- Family history of intracranial aneurysms (9-14% prevalence in ADPKD) 4, 6
Genetic Testing Strategy
Sequence PKD1 and PKD2 genes first, as these account for 93% of ADPKD cases. 2, 4 If negative and phenotype is atypical, consider expanded renal-cyst panel including HNF1B, TSC1, TSC2, VHL, and others. 3
Prognostic Assessment
If ADPKD is confirmed, calculate Mayo Imaging Classification (MIC) using height-adjusted total kidney volume to predict disease progression. 1, 4 Patients with MIC 1C-1E have rapid kidney growth (6-10% annually) and reach kidney failure at mean ages of 58.4,52.5, and 43.4 years respectively. 4
This 42-year-old patient is at the typical age of ADPKD diagnosis (27-42 years), making the diagnosis even more consistent with the clinical presentation. 4