Massive appendiceal mucinous neoplasm diagnosed after abdominal trauma: Pitfalls in imaging and diagnosis

Low grade appendiceal mucinous neoplasm (LAMN) is a rare tumor presenting typically with symptoms of acute appendicitis. A 33-year-old gentleman presented with abdominal fullness and discomfort secondary to abdominal trauma obtained during boxing training. Investigations with magnetic resonance imaging (MRI), ultrasound, and colonoscopy revealed a large cystic lesion in the ascending colon mesentery with unclear continuation with the appendix. There were no obvious features of malignancy. Laparoscopy revealed a large, firm mass connected to the appendix with enlarged lymph nodes, and the patient underwent radical resection with a right hemicolectomy. Histopathology revealed complete excision of LAMN with no lymphatic involvement. Post traumatic intra-abdominal cystic lesions pose a diagnostic challenge, and neoplastic lesions cannot be ruled out with imaging alone, even with benign appearances. Careful surgical excision and histopathological diagnosis is the only definitive method of ruling-out malignancy.