Appendix Imaging

Diseases of the appendix come in two varieties: infectious/inflammatory or neoplastic etiologies. The latter can come in the form of epithelial, neuroendocrine tumors (NETs), lymphoma, mesenchymal tumors, sarcomas, noncarcinoid NETs, neuroectodermal, nerve sheath, and metastases. The majority of cases, though, are epithelial 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 symptoms of pain in the right lower quadrant (RLQ), a palpable mass, or obstruction. 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. Appendiceal tumors almost always cause this syndrome, and if seen on imaging, the appendix requires investigation. Acute appendicitis is a prevalent cause of abdominal pain, with an estimated lifetime risk of 7 to 8%. It classically presents with periumbilical pain that localizes to the right lower quadrant (classically located half the distance between the umbilicus and anterior superior iliac spine (ASIS), known as McBurney’s point) as well as nausea, vomiting, anorexia, and fever. Acute appendicitis may result from an obstructing fecalith or some other mechanical blockage. A feared complication of acute appendicitis is perforation, with a risk of 2% at 36 hours, increasing 5% every 12 hours. With worsening inflammation, patients can develop more intense tenderness to palpation and guarding. Given the complications of acute appendicitis as well as the commonality, early accurate diagnosis is crucial.[1][2][3]