Introduction:
Retroperitoneal abscess is an unusual presentation of perforated appendicitis. A fistula between the duodenum and an abscess resulting from appendicitis has not been previously reported.
Presentation of case:
A 53-year-old Japanese man with a past medical history of hypertension and iron deficiency anemia presented with a 10-day history of fever and right lower abdominal pain, and was diagnosed with a retroperitoneal abscess secondary to perforated appendicitis. He was then treated with piperacillin and tazobactam after undergoing ultrasound-guided drainage, after which his overall condition improved. Due to iron deficiency anemia, we performed further evaluation for gastrointestinal bleeding and esophagogastroduodenoscopy showed an elevated lesion with granulomatous tissue in the duodenum, without an associated ulcer. At 10 days after abscess drainage, duodenography with contrast showed continuity between the abscess cavity and the duodenum. At 74 days after drainage, we performed laparoscopic appendectomy. Pathological examination showed granulomatous tissue inside the appendix with an inflammatory background and fecaliths infiltrated by macrophages.
Discussion:
Perforated appendicitis has various presentations and many unusual fistulae have been reported, however, a fistula between a peri-appendiceal abscess and the duodenum has not yet been reported. A retroperitoneal abscess around the duodenum and appendix should be checked to differentiate it from Valentino's syndrome.
Conclusion:
We present the rare complication of a duodenal fistula during the treatment of perforated appendicitis. The possibility of fistula formation should be considered in patients with complicated appendicitis.