Low-grade Appendiceal Mucinous Neoplasm Masquerading as Acute Appendicitis: A Case Report

Abstract

Appendiceal mucinous neoplasms, particularly Low-grade Appendiceal Mucinous Neoplasms (LAMN), are rare but important diagnostic entities as they are potential causes of a surgical abdomen. The clinical manifestations of this lesion are obscure and ill-defined, and these lesions are commonly misdiagnosed as acute appendicitis, adnexal masses, or retroperitoneal tumours. This lesion can rupture and seed mucin and neoplastic epithelium into the peritoneum, leading to Pseudomyxoma Peritonei (PMP), a serious complication with a high morbidity and mortality rate. Therefore, timely identification and treatment of LAMN are crucial for reducing the risk of PMP and improving prognosis and outcomes. Ultrasonography (USG) and Computed Tomography (CT) scans are useful methods for diagnosis; however, the diagnosis is often incidental or found intraoperatively during resection for suspected acute appendicitis. Clinical awareness of the misleading presentations of LAMN should be present in cases of a surgical acute abdomen to prevent performing a dissimilar treatment intervention. Considering the rarity of this lesion and its varied presentation, it is important to study and document this type of neoplasia in the literature. Hereby, authors report a rare case of LAMN in a 33-year-old male patient with a primary diagnosis of acute appendicitis. This case highlights the importance of having a high index of clinical suspicion of appendiceal malignancy and mucocele rupture in patients planned for appendectomy. This also emphasises the fact that all excised appendicectomy tissues should be sent for histopathological examination as they can harbor pathological changes like LAMN.