An accidental finding of a giant intra-abdominal mass.

INTRODUCTION: Mesenteric cysts are rare intra-abdominal tumours often found incidentally on imaging studies or during surgery. The clinical presentation is various with most subjects being asymptomatic, but complications can occur such as torsion, rupture, hemorrhage or obstruction of nearby structures. The etiology of mesenteric cysts remains uncertain. Complete surgical resection is preferred, although there are no specific guidelines concerning optimal treatment strategy. CASE REPORT: We present a 61-year-old male with type 2 diabetes mellitus who underwent a routine abdominal ultrasound examination which accidentally uncovered a large mass. The patient had no complaints nor any physical discomfort. Magnetic resonance imaging and computed tomography revealed a giant thin-walled cyst with multiple septa spanning 24 × 24 cm2 originating from the mesentery. The primary differential diagnosis included a mesenteric cyst, a hydatid cyst due to echinococcus or malignancy. After multidisciplinary team approach, open surgical exploration was preferred. Surgical drainage and cyst sac resection were performed without any peri- or postoperative complications. Histopathology confirmed the presence of a large mesenteric cyst, probably caused post-traumatically. The patient has made a full recovery. CONCLUSION: Mesenteric cysts can develop asymptomatically and reach enormous proportions. They are often found accidentally. Imaging studies aid in the differential diagnosis, but histopathology remains the diagnostic gold standard. Surgical resection prevails compared to a conservative approach due to the risk of complications. The choice between open or laparoscopic surgery should be determined based on the perioperative risk.