Imaging description

A nine-year-old girl with cystic fibrosis presented with chronic constipation. The patient did not have any other clinical symptoms. A radiograph of the abdomen demonstrated multiple focal, rounded lucencies along the course of the colon consistent with extensive colonic pneumatosis (Fig. 52.1). A different, asymptomatic patient was found to have pneumatosis intestinalis on a routine radiograph of the abdomen after chemotherapy and bone marrow transplant. In this case, the pneumatosis was linear in configuration, outlining the colonic wall (Fig. 52.2).

Importance

Benign pneumatosis cystoides intestinalis is a rare form of pneumatosis, characterized by multiple thin-walled microvesicular gas collections in the subserosa or submucosa of the colon. Some authors postulate that the cystic-bubbly type of pneumatosis refers to subserosal air while a linear configuration of intramural air refers to submucosal air. Radiographs demonstrate multiple small, round or linear gas collections along the course of the bowel. An ultrasound can often confirm the presence and location of the intramural air (Fig. 52.3) and may be useful for follow-up studies. A CT is rarely needed to confirm the diagnosis in asymptomatic patients. The etiology of benign pneumatosis is thought to be twofold: (1) in patients with cystic fibrosis or other obstructive pulmonary disorders, gas may dissect from ruptured alveoli along vessels and bronchi into the mediastinum, then along major vessels into the retroperitoneum and via the mesentery to the subserosa of bowel loops; (2) intramural gas may originate from intraluminal gas in the bowel, which enters the bowel wall either through a mucosal defect (trauma, ulcer, tear) or as a result of increased intraluminal pressure. In benign idiopathic pneumatosis, the specific underlying cause is typically not identified and the pneumatosis is an isolated radiologic diagnosis without associated clinical symptoms, therefore allowing conservative treatment. A well-documented complication is spontaneous rupture of a gas cyst and formation of an asymptomatic pneumoperitoneum. Treatment is usually still unnecessary. Because the cysts contain high levels (70–75%) of nitrogen, hyperbaric oxygen therapy can be beneficial if the pneumatosis does not resolve spontaneously.