Uncommon but crucial: neuroma of appendix as a rare aetiology of acute appendicitis

Introduction: Acute appendicitis is the most common surgical emergency globally. Neuroma of the appendix, a rare neural-origin tumour, often mimics the symptoms of acute appendicitis. Case Presentation: We report a case of a 39-year-old female who presented with sudden right lower abdominal pain associated with vomiting, reduced oral intake, and nausea. Examination revealed right iliac fossa tenderness, positive rebound tenderness, and a positive Rovsing's sign. Laboratory tests showed leukocytosis with neutrophilia, and abdominal ultrasound indicated acute appendicitis. An appendicectomy was performed, revealing an inflamed retrocecal appendix forming a mass clump with the tip embedded in the cecum. Microscopically, the appendiceal lumen was obliterated by uniform spindle cell proliferation in a myxoid background, with mild neutrophilic infiltration at the serosa. Immunohistochemistry revealed spindle cells positive for S100 and negative for SMA. The final diagnosis was neuroma of the appendix with serositis. Discussion: Acute appendicitis is a common surgical emergency, typically resulting from luminal obstruction. While the common causes include fecaliths, lymphoid hyperplasia, and infections, rare etiologies such as neuroma of appendix are seldom reported. Neuroma of appendix are benign nerve tissue tumours within the mucosal layer, often associated with genetic syndromes but can occur sporadically. Their presence in the appendix leading to acute inflammation presents a unique diagnostic challenge and clinical interest. Conclusion: Neuroma of appendix, though rare, should be considered a potential cause of acute appendicitis. Recognition of this entity is crucial for pathologists and surgeons to ensure accurate diagnosis and appropriate management.