Unusual radiologic presentations of malignant peritoneal mesothelioma

BACKGROUND: Malignant peritoneal mesothelioma is an unusual disease process characterized radiologically by ascites and infiltration of the peritoneum by multiple small tumor nodules. Both parietal and visceral peritoneum are involved by the multiple malignant tumor nodules. Computed tomography (CT) has been used to identify the anatomic pathology induced by the progression of this malignant process. AIM: To identify and then describe unusual CT images in patients with malignant peritoneal mesothelioma. Recognition of these unusual radiologic findings can cause the radiologist to be suspicious of this rare malignant process. METHODS: In 100 patients who were to undergo definitive treatment of malignant peritoneal mesothelioma, the findings on preoperative CT scans were catalogued. Many of these changes were repeatedly noted on the CT scans. Other pathologic CT images were less common. These unusual radiologic presentations were specially studied in this manuscript. RESULTS: Eight unusual radiologic presentations of malignant peritoneal mesothelioma were selected for study. These unusual findings included a mass occurring within a Spigelian hernia, infiltration of the splenic parenchyma by spherical mesothelioma masses, infiltration of the lower mediastinum by tumor, a mesothelioma mass within a left inguinal canal, enlarged cardiophrenic angle lymph nodes, pleural plaques associated with the progression of malignant peritoneal mesothelioma, splenic notches caused by disease surrounding the spleen, and a mass greater than 5 cm associated with the proximal jejunum and directly adjacent to the anatomic location of the Treitz ligament. CONCLUSION: There are unusual radiologic presentations of malignant peritoneal mesothelioma that are important to recognize in order to accurately diagnose this disease by CT.