A 65-year-old man on pantoprazole for 4 weeks for dyspepsia presents with fever, maculopapular rash, and acute kidney injury (creatinine 3.4 mg/dL from baseline 1.0). Urinalysis shows sterile pyuria with white cell casts. Eosinophilia is present on peripheral smear. Which diagnosis best explains this presentation?

• A Acute interstitial nephritis ✓
• B Acute pyelonephritis
• C Rapidly progressive glomerulonephritis
• D Acute tubular necrosis

Explanation

The classic triad of drug-induced AIN is fever, rash, and eosinophilia with sterile pyuria and white cell casts. PPI is a common offending drug. Distractor B would have positive urine culture, bacteriuria, and no white cell casts. Distractor C would have red cell casts and haematuria. Distractor D would have granular/muddy brown casts, not white cell casts, and no eosinophilia.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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