Pseudomyxoma extraperitonei: a rare presentation mimicking an iliacus abscess.

Mucoceles of the appendix are very rare lesions and are occasionally associated with pseudomyxoma peritonei, a gelatinous ascites that arises from intraperitoneal rupture or degeneration of the mucocele. Rupture of a retroperitoneal mucocele of the appendix is extremely rare; pseudomyxoma extraperitonei has been previously reported in only five patients. We report a new case of pseudomyxoma extraperitonei due to mucinous adenocarcinoma of the appendix which presented initially as pyrexia of unknown origin followed by the appearance of an abdominal mass mimicking an iliacus abscess. This appears to be the first case reported as presenting in such a manner.