Collision tumor of the appendix with concomitant cecal adenocarcinoma: A case report and literature review

Abstract

Introduction

Collision tumors of the appendix are rare tumors consisting of two distinct pathologies arising from different cell lines simultaneously. The most common type is the coexistence of a neuroendocrine tumor (NET) with a low-grade appendiceal mucinous neoplasm (LAMN). We report a unique case of appendiceal collision tumor with synchronous cecal intra-mucosal carcinoma and pulmonary sarcoidosis.

Case presentation

A 57-year-old man presented to the clinic with vague abdominal pain. Upon investigation, a colonoscopy showed a large cecal mass, and a computed tomography scan showed a polypoid cecal mass, a dilated, fluid-filled appendix, multiple bi-lobar lung nodules, and enlarged mediastinal and hilar lymph nodes (LN). Following discussion in a multi-disciplinary team tumor board meeting, the patient underwent laparoscopic right hemicolectomy and mediastinoscopy with mediastinal LN biopsy. His postoperative hospital stay was uneventful. Histopathology revealed a cecal tubulovillous adenoma with intra-mucosal carcinoma. A collision tumor of the appendix was found, including an in situ LAMN and a < 5 mm NET. The mediastinal LN showed sarcoidosis. There was no evidence of recurrence after a two-year follow-up.

Discussion

Previous reports of appendicular collision tumors show high variability in the presentation and management. While some present with acute appendicitis, others may have a subacute or atypical presentation. Management ranges from appendectomy to cytoreductive surgery and hyperthermic intraperitoneal chemotherapy, depending on the tumor stage.

Conclusion

Collision tumors of the appendix are rare, with highly variable presentation and management. There are no clear management or surveillance guidelines, given their rarity. Thus, treatment should be individualized.