Complicated benign cystic mesothelioma of mesoappendix misdiagnosed as an appendiceal abscess in a postpartum period woman

Benign cystic mesothelioma is an uncommon tumor arising from the peritoneal mesothelium. It is characterized by multilocular grapelike, thin-, and translucent-walled cysts, or a unilocular cyst lined by benign mesothelial cells. It occurs predominantly in women of reproductive age, and shows a predilection for the surface of the pelvic peritoneum or visceral peritoneum. Patients usually present abdominal pain and palpable mass, but many cases have been found incidentally during laparotomy. Definite preoperative diagnosis is known to be difficult. Benign cystic mesothelioma has a tendency towards local recurrence, although the gross microscopic features are benign. Moreover, there is controversy over whether this disease is neoplastic or reactive. Initial complete surgical resection and cytoreductive surgery for recurred cases are standard treatments. In the following report, we describe a case of complicated benign cystic mesothelioma in a postpartum woman, involving the pelvic peritoneum and mesoappendix, which was initially misdiagnosed as a periappendiceal abscess.