A 38-year-old woman has been feeling lethargic for 4 months. On physical examination, she is afebrile, and her blood pressure is 140/90 mm Hg. Laboratory findings show the serum creatinine level is 5.8 mg/dL. C3 nephritic factor is present in serum, resulting in hypocomplementemia, and the ANA test result is negative. Urinalysis shows 2+ blood and 1+ protein. A renal biopsy is done; microscopic examination shows hypercellular glomeruli and prominent ribbonlike deposits along the lamina densa of the glomerular basement membrane. Which of the following forms of glomerulonephritis is most likely to be present in this patient?
A 38-year-old woman has been feeling lethargic for 4 months. On physical examination, she is afebrile, and her blood pressure is 140/90 mm Hg. Laboratory findings show the serum creatinine level is 5.8 mg/dL. C3 nephritic factor is present in serum, resulting in hypocomplementemia, and the ANA test result is negative. Urinalysis shows 2+ blood and 1+ protein. A renal biopsy is done; microscopic examination shows hypercellular glomeruli and prominent ribbonlike deposits along the lamina densa of the glomerular basement membrane. Which of the following forms of glomerulonephritis is most likely to be present in this patient?
💡 Explanation
## **Core Concept**
The question tests knowledge of glomerulonephritis types, specifically those associated with complement pathway dysregulation and unique ultrastructural findings on renal biopsy. The patient's presentation suggests a membranoproliferative glomerulonephritis (MPGN) due to the presence of hypocomplementemia and specific biopsy findings.
## **Why the Correct Answer is Right**
The patient's laboratory findings, including hypocomplementemia (low C3 levels) and the presence of C3 nephritic factor, point towards a form of MPGN that involves dysregulation of the alternative complement pathway. The renal biopsy findings of hypercellular glomeruli and "prominent ribbonlike deposits along the lamina densa of the glomerular basement membrane" are characteristic of **Dense Deposit Disease (DDD)**, a subtype of MPGN type II. DDD is known for its association with C3 nephritic factor, leading to persistent activation of the alternative complement pathway, and its distinctive ultrastructural findings.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option would be incorrect if it does not match the description of DDD or another form of MPGN that fits the clinical picture. Without specific details on A, B, and C, we infer based on the provided scenario.
- **Option B:** If this option does not align with DDD or another appropriate MPGN subtype based on clinical and biopsy findings, it would be incorrect.
- **Option C:** Similarly, if this does not match the provided clinical scenario, particularly the biopsy and laboratory findings indicative of DDD, it would be incorrect.
- **Option D:** This would be incorrect if it suggests a different primary diagnosis not supported by the clinical presentation, laboratory findings, or biopsy results.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **Dense Deposit Disease (DDD)**, a form of MPGN, is characterized by the presence of C3 nephritic factor leading to hypocomplementemia, and its hallmark biopsy finding is the "dense deposit" within the glomerular basement membrane, giving it a ribbon-like appearance. This condition often presents with hematuria, proteinuria, and renal failure.