Science and Education Publishing American Journal of Medical Case Reports 2374-216X 4 12 2016 12 21 Giant Peritoneal Inclusion Cyst of the Abdominopelvic Cavity, a Very Rare Case Report and Literature Review 371 375 EN Jhon Paul Castillo León General Surgeon, Department of General Surgery of Metropolitan Hospital, Quito, Ecuador Mario Montalvo Burbano María del Cisne Ordoñez Izquierdo General Medical, Isidro Ayora Hospital, Loja, Ecuador AJMCR20164121 10.12691/ajmcr-4-12-1 2016 7 23 2016 11 18 2016 12 19 The objective of this article is to present a rare case such as peritoneal inclusion cyst or a benign cyst mesothelioma, a rare injury that predominantly affects women of reproductive age, with a still unknown etiology. Materials and Methods: We present the clinical case of a 36-year-old women, asymptomatic, with a pelvic ultrasound reported free abdominal fluid in a medical checkup. In her medical history revealed that six years ago the patient underwent laparotomy for complicated appendicitis with peritonitis. The abdominal and pelvic scan showed a giant cystic lesion of 20 cm x 17 cm x 10 cm, which occupies part of the abdomen and pelvis. Result: surgical treatment was decided and the patient underwent laparotomy, achieving the complete elimination of cystic mass and small bowel resection joined the cyst was performed. The histopathology report confirmed the diagnosis of peritoneal inclusion cyst. Conclusion: location, type of injury and behavior of mesothelioma cysts should be considered as they have a high recurrence rate and are often asymptomatic.