Pneumatosis Intestinalis

Content below is from a textbook reference chapter (Sabiston Ch50 - Diverticular Disease & Miscellaneous Problems), not primary literature.

Definition and pathology

An uncommon condition manifesting as multiple gas-filled cysts of the GI tract. Cysts may be located in the subserosa, submucosa, and (rarely) muscularis layer, ranging in size from microscopic to several centimeters. Can occur anywhere along the GI tract, from esophagus to rectum, but are most common in the jejunum, followed by the ileocecal region and colon. Extraintestinal structures (e.g., mesentery, peritoneum, falciform ligament) may also be involved. Equal incidence in men and women; usually the fourth to seventh decades of life. Pneumatosis in neonates is usually associated with necrotizing enterocolitis. The cause has not been completely delineated; mechanical, mucosal, bacterial, and pulmonary hypotheses seem most plausible.

Two forms:

• Primary pneumatosis (15%) — a benign idiopathic condition, not associated with other conditions/symptoms, usually found incidentally.
• Secondary pneumatosis (85%) — associated with chronic obstructive pulmonary disease or an immunocompromised state (e.g., AIDS; after transplantation; associated with leukemia, lymphoma, vasculitis, or collagen vascular disease; in patients undergoing chemotherapy or taking corticosteroids). Other associated conditions include inflammatory, obstructive, or infectious conditions of the intestine; iatrogenic conditions such as endoscopy/jejunostomy placement; small bowel ischemia; and extraintestinal diseases such as diabetes.

On gross inspection, the cysts resemble cystic lymphangiomas or hydatid cysts. On histologic section, the involved portion has a honeycomb appearance. The cysts are thin-walled and break easily. Spontaneous rupture gives rise to pneumoperitoneum.

Clinical manifestations

Symptoms are nonspecific, and in pneumatosis associated with other disorders, symptoms may be those of the associated disease. Symptoms in primary pneumatosis intestinalis, when present, usually include diarrhea, abdominal pain, abdominal distention, nausea, vomiting, weight loss, and mucus in stools. Hematochezia and constipation have also been described. Complications associated with pneumatosis intestinalis occur in about 3% of cases and include volvulus, intestinal obstruction, hemorrhage, and intestinal perforation. Usually, pneumoperitoneum occurs in these patients, generally in association with small bowel rather than large bowel pneumatosis; peritonitis is unusual. In fact, pneumatosis intestinalis represents one of the few cases of sterile pneumoperitoneum and should be considered in the patient with free abdominal air but no evidence of peritonitis. Pneumatosis intestinalis is ominous when associated with peritonitis, mesenteric gas, or portovenous gas, as this is most concerning for life-threatening small bowel ischemia.

Diagnosis

Usually made radiographically by plain abdominal or barium studies. On plain films, pneumatosis intestinalis appears as radiolucent areas within the bowel wall, which must be differentiated from luminal intestinal gas (Fig. 50.48A). The radiolucency may be linear or curvilinear, or appear as grape-like clusters or tiny bubbles. Barium contrast or CT studies can confirm the diagnosis (Fig. 50.48B). Visualization of intestinal cysts has also been described by ultrasound.

Treatment

No treatment is necessary unless one of the very rare complications supervenes, such as small bowel ischemia, rectal bleeding, cyst-induced volvulus, or tension pneumoperitoneum. Prognosis in most patients relates to the underlying disease. The important point is to recognize that pneumatosis intestinalis is a radiographic finding, not a diagnosis — treatment should be directed at the underlying cause of the pneumatosis, and surgical intervention should be predicated on the clinical course of the patient.

Open items / gaps

• No primary literature yet in the wiki on pneumatosis intestinalis — entirely textbook-reference-derived.