Low-grade Appendiceal Mucinous Neoplasm: A Series of Four Cases

Abstract

Low-grade Appendiceal Mucinous Neoplasm (LAMN) is a rare malignant neoplasm seen in less than 0.3% of appendectomy specimens. Patients with LAMN can present with abdominal pain, mimicking appendicitis clinically. In later stages, it can rupture, leading to Pseudomyxoma peritonei (PMP). Therefore, a high clinical suspicion is needed for correct diagnosis and management. The prognosis of LAMN depends on the presence or absence of mucin/neoplastic epithelium outside the appendix. For LAMN confined to the appendix, appendectomy alone is sufficient for management, with conservative follow-up. For LAMN with extruded acellular mucin localised to the appendiceal serosa, management involves appendectomy and PMP surveillance. For all mucinous lesions of the appendix, it is essential to submit the entire appendix for histopathologic examination, thoroughly evaluating the presence of mucin/neoplastic epithelium involving the serosa/extra appendiceal tissue for accurate staging and to predict the risk of recurrence and determine further management. Here four cases of LAMN due to their rarity and clinical importance is presented. This study of four cases emphasises that the clinical diagnosis of this rare malignancy is difficult, and radiological investigations were not available as these patients presented with clinical features mimicking appendicitis. Emergency appendectomy was performed in all cases. LAMN should be considered as a differential diagnosis because if not diagnosed and treated in the early stages, it can lead to dreaded complications like PMP. The histopathological examination of all four cases of LAMN showed dissecting acellular mucin in various stages of progression in the appendicular wall, but none involving the serosa. This highlights the importance of timely surgical intervention and histopathological examination for an exact diagnosis and staging of LAMN for further follow-up or treatment.