AIR-FILLED CYSTS: Pneumatosis cystoides intestinalis (PCI) is a benign air-filled cystic formation lying in submucosal or subserous digestive tissue. PCI has been reported all along the digestive tract.Manifestations of PCI vary greatly. Some cases are asymptomatic, while others are revealed by abdominal pain or pneumoperitoneum. Outcome is usually favorable.The plain radiogram of the abdomen shows gaseous cysts of various forms lying between the liver and the diaphragm. Pneumoperitoneum may be present. Computed tomography is the ideal diagnostic test. Endoscopy may be useful for colonic localizations.Many causes have been suggested and debated. Fifteen percent of all cases of PCI are idiopathic. In the other cases, digestive tract or respiratory tract diseases, are usually the underlying cause. Exceptionally systemic disease may be associated with PCI, particularly systemic sclerosis.Surgery should be reserved for particularly severe cases.