Abstract
BACKGROUND: Cystic lymphangioma is a rare hamartoma that is especially found in the adult gastrointestinal tract. In the early stage, most patients are asymptomatic; after the onset of symptoms, there is often no specificity regarding symptoms. CASE SUMMARY: Here we report the endoscopic diagnosis and treatment of an adult patient with cystic lymphangioma of the ascending colon. One patient who came to our hospital with "dull pain in the left lower abdomen for 2 days" was initially misdiagnosed with a colon cyst according to endoscopy and then underwent endoscopic submucosal dissection. The final pathological results suggested cystic lymphangioma. One year later, no recurrence was found on re-examination via colonoscopy. CONCLUSION: Cystic lymphangioma in the gastrointestinal tract rarely occurs in adults and is easily misdiagnosed or missed. Endoscopy, imaging, histology, and immunohistochemical staining are useful for diagnosis. Surgical resection is the preferred treatment.