bubble_chart Overview

Pneumatosis cystoides intestinalis is a rare condition characterized by the presence of numerous gas-filled cysts in the submucosa or subserosa of the intestinal wall. These cysts are most commonly found in the small intestine, particularly the ileum, followed by the colon and other parts of the body.

bubble_chart Etiology

The cause of this disease remains unclear. Some authors believe that when the gastrointestinal mucosa is damaged, intestinal gas can enter the intestinal wall through the damaged area. In patients with chronic obstructive pulmonary disease, gas may enter the mediastinum from ruptured alveoli and travel along the main arteries and around the mesenteric vessels to reach the mesentery, gastrointestinal ligaments, and subserosal layer of the intestinal wall. Other authors suggest that intestinal pneumatosis is caused by bacterial infection in the lymphatic vessels of the intestinal wall. Additionally, some authors propose that malnutrition, deficiencies of certain substances in food, or disorders of carbohydrate metabolism may lead to an increase in acidic products in the intestinal lumen, which could increase the permeability of the intestinal mucosa. These acidic products may react with alkaline carbonates in the lymphatic vessels of the intestinal wall, producing carbon dioxide gas, which then exchanges with nitrogen in the blood to form gas cysts.

bubble_chart Pathogenesis

When intestinal pneumatosis is associated with peptic ulcers and pyloric obstruction, the gas cysts are located in the jejunum and ileum; if related to pulmonary diseases, apart from the mesentery and hepatogastric ligament, they primarily cluster in the ileocecal region. If occurring after colonoscopy, they are concentrated in the colon. Those located beneath the serosa resemble soap bubbles or lymphoma-like formations, appearing either as single scattered entities or in clusters, ranging in size from a few millimeters to centimeters. Submucosal lesions are not easily visible externally, and the affected intestinal segments feel spongy upon palpation, with a honeycomb-like appearance in cross-section. The cyst walls are thin, lined with a single layer of flat or cuboidal epithelial cells, resembling dilated lymphatic vessels. The cysts contain gas, which does not communicate between them. The gas composition is similar to air, except for lower oxygen levels, possibly due to absorption.

bubble_chart Clinical Manifestations

This disease can occur at any age, but is more common between 30 and 50 years old. It is more prevalent in males than females, with a ratio of approximately three times that of females. 85% of pneumatosis cystoides intestinalis are secondary to ulcers complicated by pyloric obstruction, inflammatory bowel disease, gastrointestinal tumors, and chronic intestinal obstruction, with symptoms primarily manifesting as those of the underlying disease. A small number of cases not associated with other gastrointestinal disorders are termed "primary" pneumatosis cystoides intestinalis. Most patients experience gastrointestinal symptoms at some stage of the disease, such as episodic diarrhea lasting several days or weeks, loose stools containing large amounts of mucus and bubbles, abdominal pain accompanied by constipation or thinning of stools, and hematochezia is also not uncommon. If the pneumatosis is extensive in the small intestine, malabsorption syndrome may occur, and small intestine paralysis, intussusception, or volvulus may develop. The gas cysts may sometimes rupture spontaneously, causing pneumoperitoneum without signs of peritonitis. Occasionally, this condition can lead to peritoneal adhesions, with submucosal cysts obstructing the intestinal lumen and causing intestinal obstruction.

Fulminant pneumatosis cystoides intestinalis mostly occurs in cases of acute intestinal infection and intestinal wall necrosis, and such patients often have autoimmune deficiencies. The clinical presentation includes significant toxic symptoms and signs of peritoneal irritation.

bubble_chart Auxiliary Examination

I. X-ray Examination

1. Plain Abdominal Film Supine and upright plain films should be taken, and cleansing enema is recommended before imaging. When the pneumatosis is small and few, there are often no characteristic findings. If the pneumatosis is large and numerous, especially when located beneath the serous membrane, the following may be observed: ① Clustered or wavy continuous cystic radiolucent areas of varying sizes, ranging from foxtail millet grains to grape-sized, typically 1–2 cm in diameter, can be seen along the edges of gas-filled intestinal loops. ② If pneumatosis ruptures and causes pneumoperitoneum, free gas under the diaphragm may be visible on upright films. ③ The Chilaiditi sign occurs when pneumoperitoneum causes a seasonal increase in gas volume between the diaphragm and the liver or gastric fundus, elevating the diaphragm and lowering the liver or gastric fundus, creating a significant gap. Gas-filled intestinal loops can easily rise into this gap, forming interposed loops. Pneumatosis cysts in the intestinal wall make interposition more likely, rendering the cystic radiolucent areas along the intestinal wall more distinct. This sign is highly diagnostic for the condition.

2. Barium Meal X-ray This can further clarify the findings of plain films and confirm the distribution and extent of pneumatosis. Common manifestations include: Cystic radiolucent areas of varying sizes along the edges of barium-filled intestinal loops. If the pneumatosis is beneath the serous membrane, the radiolucent areas often lie outside the contour of the barium-filled intestinal lumen. If the pneumatosis protrudes into the intestinal lumen, polyp-like filling defects with higher radiolucency may be seen along the intestinal edges. Care must be taken to differentiate these from polyps and neoplastic filling defects.

II. Fiberoptic Endoscopy

During endoscopic examination of colonic pneumatosis cystoides, rounded elevations of varying sizes can be seen beneath the mucous membrane. The mucosal surface appears smooth and intact, with a broad base and no pedicle. Pressing the lesion with the endoscope may alter its shape. Biopsy typically reveals normal mucosa, and the lesion may disappear if the cyst is ruptured during sampling.

bubble_chart Diagnosis

This disease is relatively rare, and it is seldom diagnosed clinically on its own. For patients with vague abdominal discomfort, if abdominal fluoroscopy reveals free gas under the diaphragm without signs of peritonitis, the possibility of this condition should be considered. Diagnosis primarily relies on X-ray and endoscopy.

bubble_chart Treatment Measures

There is no specific treatment method in itself. If there are no obvious symptoms, clinical observation can be conducted without the need for special treatment. Sometimes the cysts may disappear on their own. If there are obvious clinical symptoms such as abdominal discomfort, abdominal distension and fullness, diarrhea, etc., oxygen inhalation therapy can be performed. There are reports of using hyperbaric oxygen inhalation at 2.5 atmospheres, once a day for 2 hours each time, with the cysts disappearing and symptoms alleviating after 2–3 sessions. The gas within the cysts is mainly non-oxygen components, and the high concentration of oxygen in the blood eliminates the gas in the cysts through gradient diffusion. Once oxygen enters the cysts, it is quickly metabolized and utilized by the tissues, causing the cysts to disappear. Treatment for pneumatosis cystoides intestinalis when it causes intestinal obstruction. When surgical treatment is required, if the lesions are limited to a single intestinal loop, partial intestinal resection and anastomosis can be performed. If the lesions are extensive, the focus should be on relieving the obstruction.

If pneumatosis cystoides intestinalis is accompanied by other diseases such as pyloric obstruction, inflammatory bowel disease, or malignant tumors of the digestive tract, treatment should target these primary conditions.

Fulminant pneumatosis cystoides intestinalis should be treated surgically while controlling infection with broad-spectrum antibiotics and gastrointestinal decompression. The prognosis for such patients is poor, with a high surgical mortality rate.

bubble_chart Differentiation

1. Enterogenous cyst

This condition often occurs in the distal ileum, located within the intestinal wall, and is more common in children, usually presenting as a single mass.

2. Intestinal tumors and malignant tumors

Differentiation mainly relies on X-ray barium meal and endoscopic examinations. During X-ray barium contrast examination, the filling defects caused by polyps or tumors do not change in size or shape with the amount of barium contrast filling, and their density is higher than that of filling defects caused by pneumatosis. Colonoscopy and biopsy can confirm the diagnosis.

3. Intestinal lymphangioma

Surgical exploration reveals a similar appearance, except that the cyst contains fluid.