Abstract
We report an 80-year-old male with a nodular fibrous pseudotumor (NFP), a rare benign tumor typically linked to trauma, surgery, or inflammation. Unusually, it presented as a mobile peritoneal loose body (PLB) despite no relevant abdominal history. Imaging showed a well-defined oval mass (70 × 63 mm). Pathological examination confirmed NFP, showing hyalinized collagen and fibroblast proliferation without atypia. This is the first NFP presenting as a PLB at our institution. The patient underwent successful laparoscopic resection with no recurrence during follow-up. This case highlights that: NFP can mimic mobile intraperitoneal lesions, requiring distinction from malignancy; pathological confirmation is essential due to overlapping computed tomography features with metastases; and the PLB presentation expands the known etiological spectrum beyond classical triggers. NFP should be considered in the differential diagnosis of peritoneal nodules, especially in atypical scenarios.