Torsion of an accessory spleen presenting as an acute abdomen with an inflammatory mass. US, CT, and MRI findings.

Torsion of an accessory spleen is extremely rare. Only seven cases in children have been reported in the literature. This entity should be considered in the differential diagnosis of acute abdomen associated with an intraperitoneal inflammatory mass. This report describes a 10-year-old boy with severe abdominal pain and a mass that was found to be due to infarction of an accessory spleen that had twisted on its pedicle. Magnetic resonance imaging taken at two different times was helpful in detecting an inflammatory mass, while ultrasonography and computed tomography indicated only the presence of an intraperitoneal mass.