Granulomatous interstitial nephritis as a manifestation of Crohn disease.

Granulomatous interstitial nephritis is a rare extraintestinal manifestation of Crohn disease that has been described previously in 4 patients. We report a 23-year-old man with a history of Crohn disease since age 6 years who was admitted to the hospital for weight loss, fever, and bloody diarrhea in the midst of a recent flare up during the past 2 months. Investigations revealed anemia, high erythrocyte sedimentation rate, high C-reactive protein level, and an elevated serum creatinine level. Histopathologic examination of tissue specimens obtained at renal biopsy demonstrated granulomatous interstitial nephritis. Crohn disease needs to be in the differential diagnosis of granulomatous interstitial nephritis and can be a manifestation of drug allergy or the Crohn disease itself.