Hidden Malignancy behind the Hernial Sac: Incidental Low-Grade Appendiceal Mucinous Neoplasm Discovered during Incisional Hernia Repair

Abstract

Background: Low-grade appendiceal mucinous neoplasms (LAMNs) are uncommon epithelial tumors of the appendix, often discovered incidentally during imaging, surgery, or histopathological examination. Their clinical presentation is frequently nonspecific, making preoperative diagnosis challenging.

Case Presentation: A 55-year-old male presented with multiple swellings over a previous laparotomy scar for four months. He had undergone emergency laparotomy with colorectal anastomosis for sigmoid colon carcinoma three years earlier. Clinical examination and radiological evaluation were consistent with a large incisional hernia. Contrast-enhanced computed tomography demonstrated supraumbilical herniation of omentum and divarication of recti without evidence of recurrent malignancy. Colonoscopic evaluation was normal. The patient underwent open onlay mesh repair with anterior component separation. During surgery, the appendix appeared inflamed, with a mucinous lesion involving the tip. Appendicectomy was performed. Histopathological examination revealed low-grade appendiceal mucinous neoplasm (LAMN), pathological stage pTisNx, with negative proximal margins and no lymphovascular or perineural invasion.

Conclusion: This case highlights the importance of careful intraoperative inspection during abdominal wall reconstruction procedures. Incidental appendiceal neoplasms, although rare, may be encountered unexpectedly, and timely surgical management can prevent disease progression and complications such as pseudomyxoma peritonei.