ENCAPSULATED RETROPERITONEAL PNEUMOPERITONEUM AFTER MUCOSECTOMY FOR LST - CASE REPORT

Case Presentation A 40-year-old female patient with no prior comorbidities, in good nutritional status, underwent a screening colonoscopy due to a family history of colorectal cancer. An LST (laterally spreading tumor) was found in the ascending colon, near the cecum. The lesion was elevated with saline solution and endoscopic mucosal resection (EMR) was performed using a diathermic loop in a piecemeal fashion, without complications during the procedure. On the 15th post-procedure day, the patient developed an increase in abdominal volume in the hypogastric region, which was painless. She did not present with fever, leukocytosis, or any systemic or intestinal symptoms, but had a significant abdominal bulging with a palpable mass. A CT scan revealed an expansile formation with thin walls and gas content in the right iliac fossa, medial to the ascending colon, causing an impression on the abdominal wall. After no resolution with conservative treatment, the patient underwent a videolaparoscopy on the 20th day post-mucosectomy, which revealed a loculated retroperitoneal pneumoperitoneum, with no apparent perforation or colon injury. A puncture was performed on the bulging area, releasing a significant amount of gas, with no signs of enteric fluid or feces, and the posterior peritoneum was opened by approximately 1 cm, where the gas encapsulation was located. On the 15th post-operative day following VLP (videolaparoscopy), the patient returned to the outpatient clinic with a similar painless abdominal volume increase, and imaging studies showed compatible findings. A decision was made for a laparotomy through a transumbilical incision, with findings similar to the previous VLP: a large encapsulated retroperitoneal pneumoperitoneum with only gas inside, again with no apparent perforation or colon injury. A careful and extensive dissection of the peritoneal wall was carried out, and the cavity was drained. The patient progressed well, with resolution of the condition and late post-operative imaging showing no significant findings. The pathological examination of the LST confirmed it as a tubular-villous adenoma.

Discussion Endoscopic mucosal resection (EMR) is a procedure used to remove early-stage precancerous lesions or other abnormal tissues from the gastrointestinal tract. Mucosectomy for LST is a safe and effective technique for treating sessile and flat lesions in the colon, with low recurrence or complication rates, though it occasionally results in piecemeal excision for larger lesions. This case represents a peculiar and atypical post-mucosectomy complication, with few similar cases described in the literature.

Publication History

Article published online:
25 April 2025