A primary Pseudomyxoma Peritonei is uncommon. For a long time, ovaries, colon and appendix were proposed like a site origin of these enigmatic lesions. Recent publications show that the majority of cases are due to a rupture of appendicle adenoma. We report a case of a pseudomyxoma peritonei arising in an elderly patient with a previous medical history of appendectomy undergone in infancy. The pseudomyxoma was misdiagnosed as an abdominal abscess related to colitis. In our opinion, metaplasia of the Müllerian system is a possible source of a primary peritoneal pseudomyxoma.