A clinical case of granulomatous interstitial nephritis in a young patient with nonspecific ulcerative colitis

The article describes a clinical case of granulomatous interstitial nephritis (GIN) in a 26-year-old woman with an ulcerative colitis (UC). The initial manifestation of inflammatory bowel disease (IBD) in the patient was severe abdominal bloating and pain appeared in 2018 on the background of stress. The clinical presentation was nonspecific, and irritable bowel syndrome was diagnosed. Probiotics were prescribed with minimal positive effect. Since January 2019, the patient has had frequent loose stools with mucus and streaks of blood and the diagnosis of irritable bowel syndrome have been changed to IBD. In March 2019, according to a colonoscopy with biopsy, a diagnosis of UC was established. Subsequently, it was repeatedly confirmed by colonoscopy and histological data. Treatment with 5-aminosalicylic acid (5-ASA) preparations has been prescribed. For the first time in January 2020, a slight increase in creatinine level was noticed. In August 2021, against the background of a recurrent course of UC, an increase in creatinine level by more than two times and a significant decrease in glomerular filtration rate were detected. Tubulointerstitial nephritis was diagnosed. Subsequently, a biopsy revealed a large interstitial granuloma consisting of epithelioid cells with an admixture of eosinophils and neutrophils. The diagnosis was clarified as GIN. The disease developed against the background of IBD–UC, which is atypical and necessitates ruling out other causes. During an exacerbation of UC, the patient was also diagnosed with high titers of Epstein–Barr virus. In this regard, EBV infection, as well as preparations of 5-ASA, can also be considered among the probable causes of the development of GIN. As treatment, the patient received three courses of intravenous pulse therapy with methylprednisolone, with a total dose of 9000 mg. The treatment proved effective, leading to a decrease in creatinine levels and proteinuria. Notably, the baseline therapy for UC with 5-ASA drugs was not discontinued during this period.