Abdominal actinomycosis associated with a sigmoid colon perforation in a patient with a ventriculoperitoneal shunt.

Abdominal actinomycosis causing hydronephrosis in a patient with a ventriculoperitoneal shunt is very rare. A 27- year-old female patient was admitted complaining of lower abdominal pain. She had undergone ventriculoperitoneal shunt surgery 10 years ago. Abdominal Ultrasonography and a CT scan demonstrated an inflammatory mass in the lower left quadrant of the abdomen causing obstructive hydroureter and hydronephrosis. Laparotomy revealed a diffusely infiltrating mass involving the small bowel, mesentery, and sigmoid colon, and a 1cm perforation in the sigmoid colon. Actinomycosis was diagnosed upon histological examination. After treatment with antibiotics and surgery, the patient's condition improved.