A 12-year-old girl presents to the emergency department following a skiing crash in which the left side of her mid torso hit a tree. She presents with left side lower chest and upper abdominal pain. She also complains of left shoulder pain. The most likely diagnosis is which of the following?

The spleen is the most common solid organ injured by blunt trauma. Though gastric rupture could cause the clinical presentation described, it is very rare. Rib fracture in the mid torso alone generally does not cause the referred shoulder pain, because blood does not collect under the left diaphragm, as seen in splenic injuries.