USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

Which condition is characterized by a palpable olive mass in the epigastric region?

1. Appendicitis

2. Cholecystitis

3. Congenital Pyloric Stenosis

4. Peptic ulcer disease

The correct answer is: Congenital Pyloric Stenosis

The palpable olive mass in the epigastric region is characteristic of congenital pyloric stenosis, a condition that typically occurs in infants. This condition arises when the pylorus, which is the area of the stomach that connects to the small intestine, becomes hypertrophied. This hypertrophy leads to a narrowing of the pyloric channel, causing gastric outlet obstruction. Clinically, the "olive" is described based on the shape and size of the pylorus when palpated in the abdomen, particularly felt in the upper right quadrant. Infants with congenital pyloric stenosis often present with projectile non-bilious vomiting and may exhibit signs of dehydration and electrolyte imbalances. The condition is primarily seen in infants aged 3 to 12 weeks, and a significant family history can be noted in some cases. In contrast, appendicitis would typically present with right lower quadrant pain and tenderness rather than an olive mass in the epigastric region. Cholecystitis is associated with gallbladder inflammation and pain in the upper right quadrant but does not lead to the palpable mass described. Peptic ulcer disease may cause epigastric pain but lacks the specific findings associated with the palpable olive mass indicative of pyloric stenosis. Thus