RESUMO
BACKGROUND: Mesenteric cysts are very rare abdominal growths, generally asymptomatic, and which are usually detected incidentally while performing a physical examination or an imaging test. Complications such as infections, haemorrhage, torsion, rupture, or bowel obstruction, are seldom found in this pathology, but they can be a cause of acute abdomen. The purpose of this report is to describe the characteristics and the clinical outcome of a male patient with an infected mesenteric pseudocyst of the jejunum. CLINICAL CASE: A 49 year-old male was admitted to the emergency department with 6-day onset of abdominal pain, bowel obstruction signs, palpable tumour located in the upper hemi-abdomen, systemic inflammatory response syndrome, 36,100/mm(3) white cells, 4.21 ng/ml procalcitonin, abdominal computed tomography scan with evidence of a mesenteric cystic tumour. An exploratory laparotomy was performed, finding the presence of a mesenteric pseudocyst of the jejunum with infection signs, extirpated and sent for histopathological examination. The clinical progress of the patient was satisfactory with the discharge of the patient 7 days after the surgical intervention. CONCLUSION: These cysts can debut as an acute abdomen due to haemorrhage, infection, obstruction and/or bowel perforation, complications can be life threatening if not detected and surgically treated at an early stage by performing a resection of the pseudocysts, with or without bowel resection, depending on the location and the size of the cyst.