Pathology of appendiceal tumours

Tumours of the appendix are uncommon but clinically important. The commonest appendiceal tumour is the carcinoid tumour, which is usually found incidentally during routine histopathological examination of an appendicectomy specimen. Most small carcinoid tumours have not spread at the time of diagnosis and are adequately treated by appendicectomy. A right hemicolectomy may be required for larger carcinoid tumours or those with an aggressive histological growth pattern. Tumour spread to the liver may result in development of the carcinoid syndrome. Adenomas of the appendix are benign epithelial neoplasms that can result in the development of an appendiceal mucocoele but which are cured by appendicectomy. Some appendiceal adenomas are associated with coexistent neoplasia elsewhere within the colorectum. Adenocarcinomas of the appendix may present with atypical clinical features and are often advanced at diagnosis. The prognosis of appendiceal adenocarcinoma remains poor despite treatment by right hemicolectomy + chemotherapy. Intra-abdominal tumour spread can lead to carcinomatosis peritonei or to pseudomyxoma peritonei, depending on the histological growth pattern of the primary tumour. Non-epithelial neoplasms of the appendix are rare and may present as isolated lesions or secondary to another disease process.