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April 23, 2019

Crescentic IgA nephropathy

The patient is a 17-year-old white female who presents with 2.85 grams/24 hr proteinuria, microscopic hematuria, and a creatinine of 3.2 mg/dl. She was in her normal state of health and was incidentally found to have abnormal lab values and urinalysis at a routine sport’s physical. She reports that she had noticed a little more fatigue the last few months, but had blamed this on being busy at her job after school. Figure 1 shows focal fibrinoid necrosis. Figure 2 shows moderate tubular atrophy and interstitial fibrosis. Figures 3 & 4 show a segmental cellular crescent. Figure 5 shows several red blood cell casts. Figures 6, 7, & 8 shows IgA, kappa, and lambda, respectively.

The biopsy shows a focal crescentic IgA nephropathy. Earlier editions of the Oxford classification had not found crescents to be an independent predictor of poor renal outcomes in patients with IgA nephropathy. In a more recent meta-analysis of 3096 subjects, the presence of any cellular or fibrocellular crescent was independently associated with a worse prognosis in IgA nephropathy. The Oxford classification has now added a criteria for crescents: C0 (no crescents), C1 (less than 25% of glomeruli with crescents), and C2 (greater than 25% of glomeruli with crescents). Repeat renal biopsy studies in patients with IgA nephropathy have shown that crescents, fibrinoid necrosis, and endocapillary hypercellularity are potentially reversible with immunosuppressive therapy.