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Abstract: SA-PO062

Granulomatous Tubulointerstitial Nephritis Preceding a Diagnosis of Polyarteritis Nodosa

Session Information

Category: Acute Kidney Injury

  • 102 AKI: Clinical‚ Outcomes‚ and Trials

Authors

  • Crane, Clarkson, University of California San Diego School of Medicine, La Jolla, California, United States
  • Karl, Bethany E., University of California San Diego School of Medicine, La Jolla, California, United States
Introduction

The systemic vasculitides are classified based on the size of the vessels involved and ANCA vasculitis is the most common to involve the small vessels of the kidney. Granulomatous tubulointerstitial nephritis (TIN) without glomerular involvement has been described in ANCA vasculitis but is not commonly reported with medium vessel vasculitis. We present a case of necrotizing granulomatous TIN associated with systemic polyarteritis nodosa (PAN).

Case Description

A 71-year-old female was admitted with a two-day history of purpuric lower extremity rash, abdominal pain, and AKI (serum creatinine 1.8 mg/dL from baseline 0.6 mg/dL). There was initially concern for IgA vasculitis and prednisone was started. A skin biopsy revealed leukocytoclastic vasculitis but negative IF. A kidney biopsy was notable for necrotizing granulomatous TIN but otherwise unremarkable appearance of the glomeruli.

As her AKI and overall clinical status worsened, she was started on HD. Due to worsening liver function, a liver biopsy was done showing neutrophilic inflammation but no granulomas. Rheumatologic workup notable only for ANA 1:360 (normal complements, negative ANCA, MPO, PR3, RF, cryoglobulins). Infectious workup (TB, fungal, and parasitic) was unremarkable. There was neither NSAID nor antibiotic exposure prior to the kidney biopsy. Only home medication was losartan. She received dose 2 of Moderna COVID-19 vaccination 4 weeks prior.

Her kidney function improved and dialysis was stopped, however, she developed a new foot drop. A sural nerve biopsy showed necrotizing vasculitis of a medium sized vessel. The clinical picture was felt to be most consistent with PAN. Her steroid dose was increased and she started Cytoxan per CYCLOPS protocol with subsequent clinical improvement.

Discussion

There are few prior reports of isolated TIN associated with PAN and there are often confounding exposures that can potentially explain AIN. In the present case, the early histologic diagnosis of TIN in the absence of known exposures suggests the TIN is likely associated with, and potentially secondary to, the concurrent vasculitic process. Clinically, her presentation may represent a small and medium vessel vasculitis overlap syndrome as her pathology was not entirely consistent with an ANCA-negative pauci-immune vasculitis nor PAN. Alternatively, the TIN may simply be a response to the systemic inflammatory condition.