[1603] Histopathologic Spectrum of Renal Biopsies in Patients with Inflammatory Bowel Disease

Josephine M Ambruzs, Patrick D Walker, Christopher P Larsen. Nephropath, Little Rock, AR; University of Arkansas for Medical Sciences, Little Rock, AR

Background: Renal disease as a complication of inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), has been the subject of case reports describing glomerulonephritis, secondary amyloidosis, and tubulointerstitial nephritis. However no cases series examining IBD and renal disease has been published to date. Our aim was to evaluate a large series of renal biopsies from patients with IBD to determine the spectrum and relative frequencies of IBD-associated renal pathology.
Design: A retrospective review from March 2001 to June 2012 was performed and identified 83 patients with IBD who underwent native renal biopsy. Standard processing of all biopsies included light, immunofluorescence, and electron microscopy.
Results: The cohort included 51 men and 32 women with a mean age of 46 years (range 12-80). There were 45 cases of CD and 38 cases of UC. The most common indication for biopsy was acute or progressive chronic renal failure (62.6%), hematuria (16.9%), and nephrotic-range proteinuria (15.7%). IgA nephropathy was the most common diagnosis (24.1%) followed by interstitial nephritis (19.3%), arterionephrosclerosis (12.0%), acute tubular injury (8.4%), proliferative glomerulonephritis (7.2%), and minimal change disease (4.8%). Twelve additional primary findings were represented in the remaining 24% of cases. Only one case of secondary amyloidosis was identified in a patient with CD. The frequency of IgA nephropathy in IBD was significantly higher than the 8.1% diagnostic prevalence of IgA nephropathy in all other native renal biopsies evaluated at our institution from the same time period (p=<0.0001). This IgA subgroup included 13 with CD and 7 with UC. Of the 16 cases of interstitial nephritis, 7 were classified as acute, 5 as granulomatous, and 4 as chronic. All of the cases of granulomatous interstitial nephritis had current or recent past exposure to aminosalicylates. Exposure to this class of drugs was not universal among the remaining 11 cases.
Conclusions: IBD is associated with a spectrum of renal diseases most commonly affecting the glomerular and tubulointerstitial compartments. Our series shows that IgA nephropathy is the most frequent diagnosis seen in IBD with a significantly higher diagnostic prevalence when compared to all non-IBD native renal biopsies. This may reflect a common pathogenic mechanism. Although many cases of tubulointerstitial nephritis had a history of treatment exposure to aminosalicylates, the possibility of a direct relationship with IBD cannot be ruled out.
Category: Kidney (does not include tumors)

Tuesday, March 5, 2013 8:30 AM

Proffered Papers: Section H, Tuesday Morning

 

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