The article presents the history of the disease in a 43-year man who reported to hospital because of the sudden occurrence of strong, diffuse, abdominal pain. Diagnostic tests performed in the emergency mode, including abdominal cavity US, showed no pathology. Subsequent US performed 12 hours later showed the presence of a pelvic minor tumour of adipose texture. The presence of this pathology was then confirmed by abdominal CT. Four days after admission to hospital, the patient was operated on, revealing in the HP study a partial necrosis of the gastrocolic omentum against the epiploic appendix pedicle with adipose tissue fibrosis. There were no complications in the patient in the postoperative period, and after 13 days he was discharged in good general condition. Retrospective analysis of this case demonstrates the need for considering this pathology in the differential diagnosis of acute abdomen. This case deserves attention because of the rarity of this pathology in the literature, and the interesting documentation in two different imaging techniques (US and CT).