Collision Neoplasms of the Vermiform Appendix

Abstract

Neoplasms of the vermiform appendix represent 1% of all gastrointestinal tumors, with epithelial and neuroendocrine histological subtypes being the most frequent. When two or more neoplasms with different components originate synchronically in the appendix with clear margin between them, it is called a collision tumor, with exceptional cases being reported in literature. The purpose is to present two new cases of collision tumors of the appendix and perform a review of the published literature. Two cases of an 82-year-old female and a 41-year-old male with collision tumors of the vermiform appendix are presented, with clinical presentation, radiological evaluation and surgical treatment exposed. Our results are compared with other published reports. In accordance with the other reported cases, both patients presented with low-grade appendiceal mucinous neoplasm (LAMN). Female patient with synchronous goblet cell carcinoma managed with a completion right colectomy and Hyperthermic intraperitoneal chemotherapy (HIPEC) and the other patient with well-differentiated neuroendocrine (NET) tumor managed with laparoscopic appendectomy without adjuvant treatment. Since very few cases have been reported, no diagnostic and therapeutic consensus and guidelines exist up to date. We agree that local, regional, and systemic therapies should be chosen according to the tumor that represents the worst prognosis.