British Journal of Healthcare and Medical Research - Vol. 10, No. 5 Publication Date: October 25, 2023 DOI:10.14738/bjhmr.105.15430. Ramírez-Vázquez, J. L., López-Bernal, C. A., Rosas-Zamora, A. J., Hernández-Morán, A. A., Falcón-Cancino, L. A., & Padrón-Arredondo, G. (2023). A Synchronous Tumor (Colon Adenocarcinoma and Cecal Appendage Carcinoid): Clinical Case. British Journal of Healthcare and Medical Research, Vol - 10(5). 36-41. Services for Science and Education – United Kingdom A Synchronous Tumor (Colon Adenocarcinoma and Cecal Appendage Carcinoid): Clinical Case Ramírez-Vázquez, José Luis General Surgery Resident, Manuel Ávila Camacho IMSS National Medical Center, Puebla, México López-Bernal, Carlos Alberto General Surgeon, Manuel Ávila Camacho IMSS National Medical Center, Puebla, México Rosas-Zamora, Alma Jocelyn General Surgery Resident, Manuel Ávila Camacho IMSS National Medical Center, Puebla, México Hernández-Morán, Alan Alexis Resident of Pathological Anatomy, Manuel Ávila Camacho IMSS National Medical Center, Puebla, México Falcón-Cancino, Luis Arturo General Surgery Resident, ISSSTE Mérida Hospital Clinic, Yucatán, México Padrón-Arredondo, Guillermo General Surgeon, General Hospital of Playa del Carmen, Quintana Roo, México ABSTRACT Introduction: Synchronous tumors are those primary neoplasms that appear during the diagnosis of another primary neoplasm or in the following six months, with a frequency of 9.9 to 3.5%. The tumors of the cecal appendix constitute a heterogeneous group of neoplasms with variable evolution and prognosis; they represent a small part of all gastrointestinal neoplasms, around 0.5 to 1%. Add to this a synchronous tumor, which is rare; the coexistence of colon and appendix cancer is unusual. Clinical case: A 79-year-old male underwent surgery due to intestinal occlusion. With imaging studies with a presumptive diagnosis by simple tomography of a tumor in the transverse colon at the level of the hepatic flexure, colonoscopy shows 70% stenosis in said segment. Surgical intervention was performed, performing right hemicolectomy with the anatomopathological result that reported: conventional, moderately differentiated adenocarcinoma and a cecal appendix with a microscopic finding of carcinoid tumor. Discussion: In this case, a carcinoid tumor of the appendix is documented in men, despite being more frequent in women. However, the presence of a synchronous tumor occurs more