A case of low-grade appendiceal mucinous neoplasm with infection treated with ileal resection

Introduction: Low-grade appendiceal mucinous neoplasm (LAMN) is a rare tumor found in only 0.27% of appendectomy specimens. It is often misdiagnosed as appendicitis, and patients can remain asymptomatic for years, delaying treatment. This report describes a rare case of LAMN with infection that required surgery 14 years after its initial detection without treatment. Case Report: A 54-year-old woman presented with right lower abdominal pain and fever for five days. Fourteen years earlier, a computed tomography (CT) scan revealed a cystic lesion in the appendix; however, no treatment was initiated. On admission, her temperature was 38.5 °C, with mild tenderness. Blood tests showed elevated C-reactive protein (CRP) levels, and CT imaging revealed a 9 cm inflamed cystic lesion. Antibiotics were ineffective, and the patient underwent an ileal resection. Laparotomic resection was selected due to the patient’s prior history of surgery, suspected adhesions secondary to inflammation, and the considerable tumor size. The tumor was removed intact. Histopathological analysis confirmed a LAMN with associated infection. The postoperative ileus was treated with decompression, and the patient was discharged on day 20. Conclusion: When a LAMN is removed without perforation, the risk of recurrence is minimal, and the prognosis is excellent. Therefore, early diagnosis and resection are essential. Careful surgical planning is critical to prevent tumor rupture and complications such as pseudomyxoma peritonei (PMP). This case emphasizes the importance of timely intervention.