Invasive inflammatory fibrotic polyp of the duodenum: A case report.

Background: An inflammatory fibrotic polyp (IFP) of the gastrointestinal tract is generally considered benign and noninvasive. An IFP in the duodenum is very rare. Here we report the case of an aggressive and infiltrative duodenal IFP resembling a malignancy and the patient subsequently underwent surgery. To the best of our knowledge, this is the first case of duodenal IFP invading the subserosa.

Case summary: A 50-year-old female patient presented with recurrent epigastric pain for more than 1 month. Gastroscopy revealed a mass in the duodenal bulb involving the pylorus. Endoscopic ultrasound suggested that the lesion was a hypoechoic mass involving the muscularis propria, and duodenal bulb stromal tumor was considered based on abdominal computed tomography and gastric magnetic resonance imaging findings. A distal gastrectomy was subsequently performed. Based on the histopathology and immunohistochemical results, the lesion was finally diagnosed as duodenal IFP. The patient recovered well after surgery and had no recurrence at the 27-month follow-up.

Conclusion: This duodenal IFP invading subserosa indicates that IFP has specific invasion characteristics, and accurate diagnosis is critical to avoid inadequate treatment.