Review Question - QID 215136

A 1-year-old boy is brought to the emergency department by his parents after he has been refusing food for 2 meals and has had a bloody bowel movement. The parents report that the patient has been eating solid foods and has not had any significant changes to his diet. They additionally report that the patient has not had any fevers but has been fussy all day. His temperature is 98.6°F (37.0°C), blood pressure is 90/60 mmHg, pulse is 100/min, and respirations are 24/min. The patient is fussy on exam and demonstrates tenderness with palpation to the abdomen. Fecal occult blood testing is positive. The abdominal x-ray demonstrates an intussusception, which is reduced with an air enema. The cause of intussusception is further worked up, and ectopic gastric tissue is demonstrated. Which of the following is the likely cause of this patient’s symptoms?