Abstract: FR-PO0460
A Cryptic Case of Acute Interstitial Nephritis
Session Information
- AKI: Case Reports - TMA, Vasculitis, Immune-Mediated Injury, and Systemic Disease
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 102 AKI: Clinical, Outcomes, and Trials
Authors
- Mudarres, Mohamed Fawzi, Mercy Hospital St Louis Area, St. Louis, Missouri, United States
- Strouse, Jennifer, University of Iowa Health Care, Iowa City, Iowa, United States
- Rastogi, Prerna, University of Iowa Health Care, Iowa City, Iowa, United States
- Azrieh, Bahjat, University of Iowa Health Care, Iowa City, Iowa, United States
- Khawaja, Imran, University of Iowa Health Care, Iowa City, Iowa, United States
- Swee, Melissa L., University of Iowa Health Care, Iowa City, Iowa, United States
Introduction
Granulomatous acute interstitial nephritis can mimic drug-induced or autoimmune kidney injury, yet infection remains a critical alternative when the course does not fit. This case highlights disseminated cryptococcosis presenting as steroid-refractory granulomatous AIN.
Case Description
A 55-year-old woman with insulin-dependent diabetes mellitus and chronic proton pump inhibitor use developed progressive kidney dysfunction, with creatinine rising from baseline to 3.7 mg/dL. Evaluation showed anemia, elevated inflammatory markers, high-titer ANA with isolated RNP positivity, and otherwise negative autoimmune serologies.
Kidney biopsy showed granulomatous interstitial nephritis with non-necrotizing granulomas, eosinophils, plasma cells, tubular injury, and no immune-complex deposition. Initial fungal and acid-fast bacilli stains were negative. Drug-induced AIN was presumed; the proton pump inhibitor was stopped and prednisone was started. Kidney function improved only partially, then plateaued.
Hypercalcemia prompted chest imaging, which showed nodular infiltrates and a cavitary lung lesion. Bronchoscopy identified Cryptococcus neoformans with positive fungal culture and serum cryptococcal antigen. Cerebrospinal fluid studies excluded central nervous system involvement. Re-review of deeper kidney biopsy sections with GMS and Fontana-Masson staining revealed focal fungal organisms, establishing disseminated cryptococcosis with renal and pulmonary involvement.
She received renally adjusted fluconazole for approximately 12 months, with sustained kidney recovery toward her pre-illness baseline.
Discussion
This case turns on the mismatch between a plausible diagnosis and a course that refused to fit it. PPI exposure, ANA positivity, and partial steroid response supported drug-induced or autoimmune AIN early on; persistent renal dysfunction, hypercalcemia, and pulmonary lesions argued otherwise. In granulomatous AIN, failure to recover after drug withdrawal and empiric immunosuppression should prompt renewed evaluation for infection. Reassessment shifted therapy from immunosuppression to antifungal treatment and was followed by durable renal recovery.
Serum creatinine trend