A 24 year old male patient was operated on because of intestinal obstruction 15 days after a left nephrectomy had been performed for hydronephrosis due to nephrolithiasis. His past medical history included nephrolithiasis since infancy and intermittent diarrhea. A lesion localised in the distal 20-30 cm of the ileum was characterized by intestinal stenosis and inflammation. The corresponding segment of mesentery was edematous, shortened and wrapped around the intestine. Histologic findings of the small bowel specimen are shown in the figures below.