Imaging Manifestation and Pathological Comparison of the Peritoneal Loose Body: A Case Report and Review of the Literature

Abstract

Background: Peritoneal loose body (PLB) which is also called "peritoneal mouse" is a rare disease, with only a few cases reported. PLB is mostly found due to unplanned examination, surgery, or autopsy. With the increase in abdominal imaging examinations, it was gradually recognized by us. The diagnosis of PLB has three major characteristics: free movement, no blood supply, and pathological exclusion of other tumors. Case Presentation: We reported a 66-year-old male patient with an asymptomatic freely moving peritoneal loose body. The size of the lesion was about 4*4cm. The imaging data were complete including Ultrasound, Magnetic resonance (MR), Computed tomography (CT) plain scan and enhancement. Interestingly, changes in the location of the lesion were found on follow-up CT. The lesion showed concentric circles changes on CT without obvious enhancement. MR also appeared as a multi-layer signal of concentric circles. In addition, the imaging manifestations were compared with histological pathology in this article to explain imaging characteristics. Conclusion: PLB is an uncommon disease. Through the complete imaging examination of this case, we can further understand the mobility of the lesion by changing the position. The CT and MR have characteristic concentric circle changes without obvious enhancement. The diagnosis could be confirmed before surgery, which prompted the clinical early diagnosis of the disease, and an appropriate choice between surgery and conservative treatment.