 Peritoneal mesothelioma is a rare disease representing one third of all mesothelioma and nothing is known about molecular characteristics of this disease. As main cancers, genetic heterogeneity is probable. This genomic profiling associates Comparative Genomic Hybridization CGH array, BAP1 sequencing and gene expression in order to discover a biomarker that could be used in the treatment of this rare disease. Corresponding histopathological and immunohistochemical report as all clinical data are available. All data with be merged to underline a few genes of interest on which we will focus our next investigations. Depending of our preliminary results, BAP1 mutations are expected, as it was also described in pleural mesothelioma. Mutations in oncogenic drivers that could be targeted by specific therapy will be on particular interest in management of this rare disease with bad prognosis. 