Successful conservative management of hepatic portal venous gas complicating severe immune-related gastrointestinal injury during pembrolizumab-based concurrent chemoradiotherapy for cervical cancer: a mechanistic case report

Concurrent chemoradiotherapy (CCRT) combined with pembrolizumab has become the standard treatment for high-risk locally advanced cervical cancer, increasing the need for prompt recognition of immune-related adverse events (irAEs). We report a rare case of severe gastrointestinal irAE complicated by hepatic portal venous gas (HPVG) during pembrolizumab-based CCRT. A 72-year-old woman with FIGO 2018 stage IIIC1r cervical squamous cell carcinoma developed persistent diarrhea and anorexia during treatment, followed by sudden hematemesis after the first brachytherapy session. Upper gastrointestinal endoscopy revealed diffuse gastric mucosal necrosis, while contrast-enhanced computed tomography demonstrated HPVG, intramural gastric gas, and diffuse gastrointestinal wall edema without evidence of intestinal ischemia. Gastric biopsy showed marked intraepithelial lymphocytic infiltration predominantly composed of CD8-positive T cells, consistent with pembrolizumab-induced gastrointestinal irAE. High-dose corticosteroid therapy and supportive conservative management resulted in rapid clinical and radiological resolution, avoiding surgical intervention. This case highlights that gastrointestinal irAEs may mimic conventional CCRT-related toxicities, delaying diagnosis. Furthermore, HPVG should not be considered synonymous with intestinal necrosis. Careful integration of clinical, radiological, endoscopic, and pathological findings is essential to distinguish immune-mediated gastrointestinal injury from ischemic disease and to guide appropriate management.