Delayed presentation of hypertrophic pyloric stenosis: a rare case.

Hypertrophic pyloric stenosis (HPS) is the most common cause of gastric outlet obstruction in infants, with an incidence of 1.5 to 3 per 1000 live births, and classically presents at 3 to 4 weeks of age. Delayed presentation of HPS is an extremely rare occurrence after early infancy. With the exclusion of congenital HPS, gastric outlet obstruction in childhood is a rare condition (1:100,000). We report a case of delayed presentation of HPS in a 4 1/2-year-old child in whom the pylorus was hypertrophied and appeared like an "olive," and for which pyloromyotomy was curative.