An unusual cause of unilateral hydronephrosis: invasive colonic amebiasis.

A 62-year-old man was admitted to our hospital with complaints of abdominal pain and rectal bleeding. Although the colonoscopic examination was highly suggestive of a carcinoma, the histopathological examinations were consistent with chronic inflammation. CT examination revealed a solid lesion from cecum to the ascending colon with right urethral invasion. Percutaneous right nephrostomy was performed for grade 2-3 hydronephrosis. Three days after hospitalization, ileus developed and right hemicolectomy was performed. During surgery we observed that the lesion had invaded the middle part of ureter. So the middle part of ureter was removed with side-to-side urethral anastomosis and 6F double-J catheter was placed. The histopathological findings of resected specimen were consistent with ameboma. Reviewing the literature unilateral hydronephrosis due to colonic amebiasis has not been reported.