Answer Clinical Challenge 9

  The correct answer is peritoneal loose body in the pelvis.

  The high-intensity area observed in the centre of the mass in MRI was identical to that seen in fatty tissues. The boy underwent laparoscopic surgery and a hard, white, egg-shaped peritoneal loose body that was completely free in the pelvic cavity was removed. The mass composed of many layers of laminated, fibrous tissues surrounding a central necrotic fatty lesion. The differential diagnosis is often stromal tumors or teratoma. Loose bodies are more often reported in adults compared to children.
  The general belief is that peritoneal loose bodies arise owing to torsion and separation of the appendices epiploicae, which are visceral peritoneal pouches filled with fat that exist along the anti-mesenteric tenia of the colon. Small peritoneal loose bodies rarely cause symptoms, large ones (> 5 cm) could present with many abdominal symptoms. Surgical removal is advised for large and symptomatic peritoneal loose bodies.