Malignant peritoneal mesothelioma in a pediatric patient presenting as traumatic hemoperitoneum

Primary diffuse malignant peritoneal mesothelioma (MPM) is a rare malignancy, especially in pediatric patients. We describe a 15-year-old girl with diffuse MPM presenting with bloody ascites, anemia, and abdominal pain, who had a history of blunt abdominal injury about 3 days before admission. Emergent computed tomographic (CT) scans revealed massive ascites with multiple high-density mass-like lesions occupying the mesentery and omentum. The initial clinical presentation was misdiagnosed as traumatic hemoperitoneum. The patient underwent exploratory laparotomy and histologic diagnosis was established by immunohistochemistry.