Peritoneal loose bodies and the differentiation of fatty abdominal and pelvic lesions

Peritoneal loose bodies (PLBs) have been sparingly documented within the surgical and radiologic literature, with 38 cases reported to date. A 67-year-old male presented to urology for the management of an asymmetric prostatic nodule. Imaging incidentally identified a well-circumscribed mass of low T2 signal intensity with a small fatty core in the left lower quadrant close to the sigmoid colon; malignancy was in the differential. The mass grew slightly over the next year. A diagnostic laparoscopy retrieved a free floating 4 × 4 cm benign mass from the pelvis, identified as necrotic fat with areas of dystrophic calcifications. PLBs are often a diagnostic dilemma without surgical intervention. Here we present a diagnostic algorithm based on a comprehensive literature review and our case to help better identify unknown abdominal and pelvic fatty masses and to avoid surgery strictly for diagnosis, especially for patients that are not ideal surgical candidates. Using this algorithm, the mass in the patient presented here could have been accurately characterized without invasive diagnostic measures.