Peritoneal 'mice' spotted
- A social post highlighted peritoneal loose bodies — small, free‑floating calcified nodules that can mimic disease. - These 'peritoneal mice' may grow as large as 10 cm and are sometimes removed laparoscopically for diagnosis. - Because they can appear tumour‑like on imaging, surgeons may opt for removal to resolve symptoms and confirm benignity (x.com)
The abdomen is lined by a slick membrane called the peritoneum, and on rare occasions a small bit of fat can break loose, harden and roll freely inside it like a pebble. (my.clevelandclinic.org) Doctors call those nodules peritoneal loose bodies, or “peritoneal mice,” and case reports describe them as detached epiploic appendages — fat tags on the colon — that twist, lose blood supply, separate and then calcify over time. (pmc.ncbi.nlm.nih.gov) Most are found by accident during surgery, scans or autopsy and are usually small, but several reviews define “giant” peritoneal loose bodies as larger than 5 centimeters. (pmc.ncbi.nlm.nih.gov) That size matters because a smooth, round mass in the pelvis can look like a tumor on computed tomography or magnetic resonance imaging, especially when it has a dense calcified center. (pmc.ncbi.nlm.nih.gov) Radiologists look for clues that the mass is benign: a clear fat plane separating it from nearby organs, no contrast enhancement, and sometimes a change in position between scans taken days apart. (pmc.ncbi.nlm.nih.gov) When patients have pain, urinary symptoms or diagnostic uncertainty, surgeons sometimes remove the mass laparoscopically through small incisions and confirm the diagnosis with pathology. (pmc.ncbi.nlm.nih.gov) Published case reports describe giant loose bodies measuring about 5 to 6 centimeters, and one review noted that masses above 50 millimeters are especially uncommon. (pmc.ncbi.nlm.nih.gov) The gross appearance is strikingly uniform across reports: a white or pale gray oval body with a smooth surface, often compared in pathology descriptions to a boiled egg because of its firm outer layer and central core. (pmc.ncbi.nlm.nih.gov) The practical takeaway for clinicians is narrow but important: a mobile, well-circumscribed calcified pelvic mass is not always cancer, and sometimes the “tumor” turns out to be a loose body rolling in the peritoneal cavity. (www.eurorad.org)
