Appendiceal tumors are rare and lack specific clinical manifestations, making them prone to misdiagnosis or missed diagnosis. They are often identified incidentally during appendectomy procedures or postmortem examinations.
Histological Classification
Appendiceal tumors can broadly be categorized into epithelial-derived tumors (e.g., adenomas or adenocarcinomas) and non-epithelial-derived tumors (e.g., neuroendocrine tumors or lymphomas). Epithelial-derived tumors are typically further subdivided based on mucin production, as mucinous and non-mucinous tumors exhibit distinct biological behaviors and oncological outcomes. According to the World Health Organization (WHO), most non-invasive epithelial-derived lesions are classified as low-grade appendiceal mucinous neoplasms (LAMNs). Histologically, LAMNs are characterized by well-differentiated adenomas that can spread beyond the appendix in a malignant fashion. High-grade appendiceal mucinous neoplasms (HAMNs) show greater cellular atypia and are more aggressive compared to LAMNs. Appendiceal tumors encompass five major histopathological subtypes: neuroendocrine tumors (NEN), which are non-epithelial-derived, and mucinous tumors, goblet cell adenocarcinomas (GCA), colonic-type (non-mucinous) adenocarcinomas, and signet ring cell carcinomas, all of which are epithelial-derived.
Clinical Manifestations
Symptoms in patients with appendiceal tumors are typically nonspecific, making them challenging to diagnose preoperatively. In most cases, these tumors are discovered incidentally during surgery or through pathological examination of surgical specimens. Advanced disease may present with symptoms such as fatigue, weight loss, abdominal distension, and chronic abdominal pain. It may also lead to appendicitis, bowel obstruction, or symptoms related to abdominal or pelvic masses.
Treatment
Treatment strategies for appendiceal tumors depend on the patient's histopathological type, disease progression, extent of lesion involvement, and clinical circumstances. Surgical intervention constitutes the primary treatment approach.