Unusually rapid growth of a duodenal muco-submucosal elongated polyp: A case report.

BACKGROUND: Muco-submucosal elongated polyps (MSEPs) are rare benign gastrointestinal lesions, typically reported in the colon and seldom observed in the small intestine. These polyps are generally slow-growing and asymptomatic, making diagnosis and management challenging. Rapid enlargement of MSEPs in the duodenum is particularly rare and may raise suspicion for neoplastic potential. CASE SUMMARY: We report the case of a 64-year-old female who presented with nausea and abdominal pain. Abdominal computed tomography revealed a soft tissue density in the descending duodenum. Upper endoscopy performed 15 months earlier had identified a 1.5-cm mucosal elevation in the second portion of the duodenum. On follow-up endoscopy, the lesion had enlarged significantly into a 10-cm elongated, pedunculated polyp. Endoscopic submucosal dissection was performed for complete en bloc resection. Histopathology confirmed the diagnosis of a MSEP, with no evidence of malignancy. Surveillance endoscopy performed one year after resection showed no recurrence. CONCLUSION: Although MSEPs are typically benign, our case demonstrates that rapid growth may occur. This highlights the importance of continued endoscopic surveillance and early intervention, even in asymptomatic patients, to prevent potential complications and ensure timely diagnosis.