Peritoneal loose body

Case contributed by Ammar Haouimi
Diagnosis almost certain


Right renal colic.

Patient Data

Age: 40 years
Gender: Female

Small rounded well-defined peritoneal nodule of fatty density with peripheral calcification located in the right iliac fossa with no enhancement. Evidence of medial displacement of the nodule from non-enhanced to enhanced CT.

Small right renal stone with no hydronephrosis.

A small cystic structure in the right iliac fossa adjacent to the ovary (? ovarian/paraovarian cyst). Follow-up +/- MRI were requested.

Annotated image

Annotated images:

  • green arrow: peritoneal nodule on non-enhanced, CT attenuation value around -41 HU
  • white arrow: showing the same peritoneal nodule on enhanced CT, displaced medially

Case Discussion

Peritoneal loose bodies or peritoneal mice are defined as calcified pieces of necrotic tissue within the peritoneal cavity. Usually asymptomatic. They are formed by the torsion and autoamputation of epiploic appendages.

Acute torsion produces epiploic appendagitis which is normally self-limiting. However, chronic torsion results in ischemia and subsequent calcification, fibrosis and autoamputation of the appendage with it then being released into the peritoneal cavity. 

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