[Prepyloric annular diaphragm in the adult].

A case of prepyloric myo-mucosal annular diaphragm in a 47-yr-old woman with a 4-month history of subocclusion is presented. A "distal hourglass" gastric deformity was present, along with gastritis and marked spasm. The case is included in a survey of the recent literature and classed as a transitional form lying between ring diaphragm and annular hypoplasic stenosis of the antrum.