Atypical muscle hypertrophy in pyloric stenosis.

Four types of atypical hypertrophy in pyloric stenosis in 17 infants are described. In all instances, the antropyloric deformity differs from that in the classic case, and usually delays early diagnosis. However, it is important that these forms of muscle hypertrophy be appreciated, for just as in the classic case, pyloromyotomy is curative. The radiologist is in the best position to make the diagnosis providing he is aware of the four atypical configurations we have encountered: (1) persistent lesser curve mass or identation; (2) funnel-shaped antrum; (3) spiculated antrum; and (4) pyloric niche/diamond sign.