These are pulsion type diverticula which occur in the distal 10cm of the esophagus. Like the Zenker's diverticulum, they result from motor abnormalities of esophageal peristalsis which cause uncoordinated relaxation of the lower esophageal sphincter. The resulting increase in intraluminal pressure results in herniation of mucosa and submucosa through the muscular esophageal wall. These diverticula can become quite large but are minimally symptomatic.
Complaints are primarily of dysphagia and regurgitation as well as symptoms related to mass effect.