Beyond the Inflamed Appendix: Low-Grade Appendiceal Mucinous Neoplasm—Emphasis on Macroscopic Findings

TL;DR

This paper discusses a rare appendix tumor that mimics appendicitis and can lead to serious complications if not properly diagnosed.

Contribution

The paper emphasizes the importance of macroscopic findings in diagnosing low-grade appendiceal mucinous neoplasms.

Findings

LAMNs can present with symptoms similar to acute appendicitis but may lead to pseudomyxoma peritonei.

Macroscopic examination of the appendix is crucial for identifying LAMNs and preventing missed diagnoses.

Complete embedding and meticulous gross examination are necessary to detect peritoneal dissemination.

Abstract

Low-grade appendiceal mucinous neoplasms (LAMNs) are uncommon epithelial tumors that frequently present with symptoms indistinguishable from acute appendicitis, yet may progress to pseudomyxoma peritonei with significant long-term morbidity. We report the case of a 51-year-old male who presented with periumbilical pain, nausea, and fever. Although clinical findings suggested acute appendicitis, abdominal ultrasound demonstrated cystic dilation of the appendix, raising suspicion for appendiceal mucocele. Appendectomy revealed a markedly cystic, pearly appendix with multifocal wall discontinuities and mucinous exudate, resulting in complete distortion of normal anatomy. Histological examination reflected LAMN with extra-appendiceal spread. Early postoperative reoperation due to free intra-abdominal fluid revealed pseudomyxoma peritonei. This case underscores the diagnostic challenge of LAMN, highlights the critical role of meticulous gross examination and complete embedding, and emphasizes that subtle macroscopic findings may herald clinically significant peritoneal dissemination.

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