Psoas abscess following acute appendicitis due to Proteus mirabilis and Klebsiella pneumoniae

The common sites of abscess formation complicating perforated acute appendicitis are well known. However, localization of these abscesses to the psoas muscle is rare. In our case, a 36-year-old black male refugee attended the emergency department of our hospital complaining of abdominal pain after falling from a truck. His history revealed two former operations on the lower abdomen performed in Sudan. Computerized tomography of the abdomen that followed displayed the formation of a psoas abscess. As a result, the patient underwent exploratory laparotomy which identified perforation of the appendix retroperitoneally. A culture of the abscess specimen disclosed the presence of Klebsiella pneumoniae and Proteus mirabilis. In addition to describing this case, we also briefly review the literature for retroperitoneal psoas abscesses.