Benign multicystic peritoneal mesothelioma is a rare malignancy with unknown etiology, first described in 1980, which have been reported to date about 150 cases in the literature. Although the term "benign", used mainly to distinguish it from the classic malignant mesothelioma, a more aggressive cancer, is considered "borderline" in terms of aggression: it tends to local recurrence but cases of lymph node metastases or in other locations at a distance are not described. The symptoms are often vague and nonspecific (abdominal pain, enlarged abdomen and ascites). The common diagnostic imaging techniques (CT, MRI) may appear similar to ovarian or peritoneal cancer by more aggressive mesenchymal neoplasms. Histological examination, accurately with the aid of immunohistochemical techniques, is therefore essential for diagnosis. Treatment is surgical and consists of peritonectomy. After surgery, the prognosis is generally good. In 50% of cases may have local recurrences; so rigorous follow-up is indicated.