Renal involvement in Crohn's disease: granulomatous inflammation in the form of mass lesion.

Extraintestinal manifestations of Crohn's disease (CD) are varied and concentrated mainly to the skin and eye. Urinary tract or renal involvement is extremely rare. Herein we report on a case of renal lesion of a 50-year-old woman with a 15-year history of CD. Abdominal computed tomography scan of the patient identified heterogeneous multinodular mass lesions in the left kidney. Histology proved classic granulomatous inflammatory nodules with multinucleated giant cells, eosinophils, plasma cells, epithelioid cells, and spindle-shaped myofibroblasts in the areas, where the computed tomography scan indicated. After the extensive PubMed search in the literature, this is the first macroscopically documented and histologically proved, mass-like renal involvement in CD. From now on, differential diagnostics of renal mass lesions in CD should include the tumor-like, Crohn's-type granulomatous inflammation as direct kidney manifestation of the disease.