Background: We found a case of submucosal tumor of the appendix opening. Endoscopic submucosal dissection (ESD) proved to be coprolith intercalation in the appendix. Thus, the internal section of the appendix wall was removed and appendectomy was performed. Conclusion: Appendix coprolith incarceration may be misdiagnosed as cecal submucosal tumor. Endoscopic appendectomy and appendectomy can be used for the differential diagnosis and treatment of these lesions.