The case of a Peruvian 15-year-old male with a left-flank abdominal mass suspected to be a peritoneal pseudomyxoma is presented. The patient underwent a R0 surgery, and the pathology review showed a benign multicystic peritoneal mesothelioma. Characterized by recurrent mesothelial peritoneal cysts originating in the epithelial and mesenchymal elements of mesothelial tissue, this benign tumor is unusual among young males.