The 58-year-old female patient went to the emergency department of Liaocheng People's Hospital for "abdominal pain for 1 day" and was in good health. Physical examination showed mild tenderness in the lower abdomen, no rebound pain and muscle tension, normal intestinal sounds, and no sign of peritoneal irritation. Colonoscopy revealed multiple mucosal bulges in the transverse colon, sigmoid colon and rectum, 0.4-2.0 cm in diameter, translucent and smooth in surface (Figure 1, indicated by arrows). The axial position of plain abdominal CT scan showed clusters or vesicle-like low-density gas shadows in the colon wall corresponding to the endoscopic position (Figure 2, indicated by arrows); The multiplanar reconstruction images showed that a small amount of scattered free gas shadows could be seen around some diseased intestines and in the abdominal cavity (Figures 3 and 4, indicated by arrows). Combined with endoscopic and imaging findings, the final diagnosis was colonic balloon tumor combined with pneumoperitoneum. In view of the absence of fever, vomiting, obvious abdominal distension and peritoneal irritation, and stable vital signs, the patient was treated conservatively, including fasting, fluid rehydration, correction of water and electrolyte disorders and close observation, and the abdominal symptoms were significantly improved and the patient was successfully discharged. After 6 months follow-up, the patient had no recurrence or other digestive tract discomfort. There was no change in colonic air cyst after imaging review, and the free gas in the abdominal cavity was completely absorbed.
