[Benign cystic mesothelioma of the peritoneum].

Histological, histochemical and ultrastructural analysis of a rare benign tumour of peritoneum, called "cystic mesothelioma", is performed. Cystic mesothelioma is characterized histologically by a combination of cystic, papillary and adenomatoid structures; mesothelial cell signs are seen ultrastructurally.