{
  "abstract": "Introduction Inflammatory bowel diseases (IBD) comprise Crohn’s disease, ulcerative colitis, and IBD-unclassified (IBDU). Although primarily affecting the gastrointestinal tract, extraintestinal manifestations (EIMs) occur in 6-46% of patients, most frequently involving the joints, eyes, skin, liver, and biliary tract. Renal EIMs are reported in 4-23% of adults with IBD, while their prevalence in children remains uncertain. 1 Renal involvement may arise as a direct manifestation of systemic inflammation or as a complication of treatment.2 The most frequent renal pathologies include nephrolithiasis, tubulointerstitial nephritis, glomerulonephritis, and amyloidosis.1 Granulomatous interstitial nephritis (GIN) is a particularly rare EIM of Crohn’s disease, accounting for 0.5-0.9% of renal cases, and is most often drug-induced, especially by 5-aminosalicylic acid (5-ASA).3 However, non-drug-induced cases have also been described in both adults and children.4Case Presentation We report the case of a 15-year-old female diagnosed in November 2023 with IBD-U, presenting with pancolitis and histological evidence of moderate inflammation with granuloma formation in the left colon. Small bowel MRI demonstrated no terminal ileum involvement. The patient’s initial IBD treatment included oral prednisolone and mesalamine, achieving clinical remission and mucosal healing by September 2024, at which point mesalamine was discontinued. Concomitantly, at diagnosis, blood tests showed mild renal impairment with raised creatinine (81 µmol/L), while urine output and blood pressure were normal, and there were no clinical symptoms. Baseline investigations for abnormal creatinine were unremarkable. The patient underwent regular gastroenterology follow-up visits, during which renal function was repeatedly monitored, showing fluctuating levels of urea and creatinine over time. In summer 2025, the patient experienced a relapse characterized by abdominal pain, diarrhoea, fatigue, poor appetite, and weight loss.. Simultaneously, the creatinine level increased further, reaching its peak value of 123 µmol/L. A reassessment colonoscopy was planned and, in view of the persistent renal function abnormalities, she was referred to the paediatric nephrology unit for further diagnostic evaluation. Although the patient remained asymptomatic from a renal perspective and all repeated baseline evaluations were normal, a renal biopsy was performed in October 2025. It showed marked interstitial inflammatory infiltrate with tubulitis and tubular injury, with epithelioid histiocytes probably associated with a disrupted tubule. This was likely an extraintestinal manifestation of Crohn’s disease or a complication of 5-ASA use. Colonoscopy revealed active inflammation, subsequently confirmed at histology as Crohn’s colitis with ill-defined granulomas. Extensive investigations for infectious and systemic granulomatous diseases, including tuberculosis, sarcoidosis, and ophthalmology evaluation for uveitis, were all negative. A diagnosis of acute tubulointerstitial nephritis with early granulomatous formation was made. The case was discussed at a multidisciplinary team meeting involving gastroenterologists and nephrologists, and upon completion of investigations the patient was commenced on oral corticosteroids. She will continue follow-up in the outpatient clinic, with biologic therapy with anti-TNF to be considered if required.Conclusion This case illustrates a rare instance of granulomatous interstitial nephritis associated with Crohn’s colitis, emphasizing the need for systematic renal monitoring in paediatric IBD and the crucial role of MDT collaboration in managing complex presentations.References Corica D, Romano C. Renal involvement in inflammatory bowel diseases. J Crohns Colitis 2016.Pardi DS, Tremaine WJ, Sandborn WJ, et al. Renal and urologic complications of inflammatory bowel disease. Am J Gastroenterol 1998.Itoh N, Kasuno K, Yasutomi M, et al. Crohn’s disease with granulomatous interstitial nephritis as an extraintestinal complication from the time of the diagnosis. Intern Med 2025.Mohamed MMB, Flores-Santiago J, Perincheri S, et al. Granulomatous interstitial nephritis in a treatment-naïve patient with ulcerative colitis. Ren Fail 2022.",
  "authors": [
    {
      "affiliations": [
        "Paediatrics Residency, University of Milan-Bicocca, Monza, Italy",
        "Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK"
      ],
      "name": "Carla M Grimaldi"
    },
    {
      "affiliations": [
        "Paediatric Nephrology Unit, Great Ormond Street Hospital for Children, NHS foundation Trust, London, UK"
      ],
      "name": "Asheeta Gupta"
    },
    {
      "affiliations": [
        "Great Ormond Street Hospital"
      ],
      "name": "Thivya Sekar"
    },
    {
      "affiliations": [
        "Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK",
        "Paediatric Gastroenterology Unit, The Royal London Children’s Hospital, Barts Health NHS Trust, London, UK"
      ],
      "name": "Nicholas M Croft"
    },
    {
      "affiliations": [
        "Paediatric Gastroenterology Unit, The Royal London Children’s Hospital, Barts Health NHS Trust, London, UK"
      ],
      "name": "Sophie Cox"
    },
    {
      "affiliations": [
        "Paediatric Gastroenterology Unit, The Royal London Children’s Hospital, Barts Health NHS Trust, London, UK"
      ],
      "name": "Angela Cole"
    },
    {
      "affiliations": [
        "Paediatric Gastroenterology Unit, The Royal London Children’s Hospital, Barts Health NHS Trust, London, UK"
      ],
      "name": "Sandhia Naik"
    },
    {
      "affiliations": [
        "Paediatric Gastroenterology Unit, The Royal London Children’s Hospital, Barts Health NHS Trust, London, UK"
      ],
      "name": "Ahmed Kadir"
    },
    {
      "affiliations": [
        "Paediatric Gastroenterology Unit, The Royal London Children’s Hospital, Barts Health NHS Trust, London, UK"
      ],
      "name": "Protima Deb"
    },
    {
      "affiliations": [
        "Paediatric Gastroenterology Unit, The Royal London Children’s Hospital, Barts Health NHS Trust, London, UK"
      ],
      "name": "Daniel Crespi"
    },
    {
      "affiliations": [
        "Paediatric Gastroenterology Unit, The Royal London Children’s Hospital, Barts Health NHS Trust, London, UK"
      ],
      "name": "Roxana Mardare"
    },
    {
      "affiliations": [
        "Paediatric Gastroenterology Unit, The Royal London Children’s Hospital, Barts Health NHS Trust, London, UK",
        "Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK"
      ],
      "name": "Farah M Barakat"
    }
  ],
  "title": "OC42 Granulomatous interstitial nephritis in paediatric Crohn’s disease. A case report",
  "uid": "cd585068-87c3-560e-9aeb-c658f27d24dc"
}