An accessory spleen is a relatively common condition, but the torsion thereof is extremely rare, with only nine pediatric cases reported in the literature. This paper describes a case of an accessory spleen that was found to be necrotic during an emergency laparotomy in a 14-day-old female infant with signs of acute abdomen. To our knowledge, this is the youngest reported patient. The etiology of the necrosis was thrombosis of its trophic vessels, secondary to its pedicle torsion. The literature is also reviewed.