Appendix Imaging

Diseases of the appendix present in two varieties: infectious/inflammatory and neoplastic etiologies. The latter can present in the form of epithelial, neuroendocrine tumors (NETs), lymphoma, mesenchymal tumors, sarcomas, and metastases. Most neoplastic causes are epithelial tumors and NETs, with the former occurring in middle-aged or older adults and the latter occurring in younger patients. Though neoplastic processes of the appendix are typically asymptomatic, they can grow to cause obstruction, eventually resulting in symptoms of acute appendicitis. They can also produce vague pain symptoms in the right lower quadrant (RLQ) or a palpable mass. In severe cases, especially with mucinous neoplasms, they can cause pseudomyxoma peritoneii, which characteristically presents as mucin in the peritoneum and serosa of abdominal or pelvic organs. Acute appendicitis is a prevalent cause of abdominal pain, with an estimated lifetime risk of 7 to 9%. It classically presents with periumbilical pain that localizes to the right lower quadrant and nausea, vomiting, anorexia, and fever. The right lower quadrant pain is typically located half the distance between the umbilicus and anterior superior iliac spine (ASIS), known as McBurney’s point. Acute appendicitis may result from an obstructing fecalith or another typically mechanical obstruction. A feared complication of acute appendicitis is perforation, with a risk of 2% at 36 hours, increasing by 5% every 12 hours. With worsening inflammation, patients can develop more intense tenderness to palpation and guarding. Given the complications of acute appendicitis, an early, accurate diagnosis is crucial.