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Appendiceal neoplasm

Updated May 25, 2025

What's new

The American Society of Colon and Rectal Surgeons (ASCRS) has updated its guidelines for the management of appendiceal neoplasms. Appendectomy is recommended if a grossly abnormal appendix is found during an unrelated abdominal operation. Interval appendectomy following complicated appendicitis is typically recommended in adults over 40 years of age or when imaging suggests a malignant process. Appendectomy alone is appropriate for low-grade appendiceal mucinous neoplasms with negative margins and no evidence of perforation or peritoneal involvement. Right hemicolectomy is recommended for nonmetastatic adenocarcinoma but does not provide a survival benefit in the presence of peritoneal spread. Systemic chemotherapy may be offered to improve survival in patients with metastatic, lymph node-positive, high-grade neoplasms, and adenocarcinoma with peritoneal metastases. Intraperitoneal chemotherapy following cytoreductive surgery can be considered to reduce the risk of peritoneal disease recurrence. Long-term data on minimally invasive aerosolized approaches remain limited. .

Background

Overview

Definition

Appendiceal neoplasms are abnormal growths that occur in the appendix. They encompass a range of tumors, including low-grade appendiceal mucinous neoplasm, high-grade appendiceal mucinous neoplasm, and mucinous adenocarcinoma.

Pathophysiology

The pathophysiology of appendiceal neoplasms is not fully understood, but it is believed to involve genetic mutations that lead to the uncontrolled growth and division of cells in the appendix.

Epidemiology

The incidence of appendiceal neoplasms in the US is estimated at 0.93 per 100,000 person-years from 2000 to 2017.

Risk factors

Risk factors for appendiceal neoplasms include advanced age, cystic fibrosis, and familial adenomatous polyposis, although the risk factors are not comprehensively defined.

Disease course

Clinically, appendiceal neoplasms often present with non-specific symptoms such as abdominal pain, changes in bowel habits, and weight loss. In some cases, they may be discovered incidentally during imaging or surgery for other conditions.

Prognosis and risk of recurrence

The prognosis of appendiceal neoplasms can vary widely and is influenced by factors such as the stage of the disease at diagnosis and the specific type of neoplasm.

Guidelines

Key sources

The following summarized guidelines for the evaluation and management of appendiceal neoplasm are prepared by our editorial team based on guidelines from the American Society of Colon and Rectal Surgeons (ASCRS 2025) and the National Comprehensive Cancer Network (NCCN 2021).

Diagnostic investigations

Diagnostic imaging

As per ASCRS 2025 guidelines:

Consider obtaining neuroendocrine tumor-specific imaging in patients with lesions > 2 cm, symptoms of carcinoid syndrome, and findings indeterminate for metastatic disease on other imaging studies.

Obtain cross-sectional imaging with CT or MRI at diagnosis of appendiceal epithelial neoplasms and routinely for postoperative surveillance.

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Diagnostic procedures

Colonoscopy: as per ASCRS 2025 guidelines, perform colonoscopy in patients with confirmed or suspected appendiceal neoplasms.

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Medical management

Systemic chemotherapy

As per ASCRS 2025 guidelines:

Consider offering systemic chemotherapy in patients with metastatic, lymph node-positive, high-grade appendiceal neoplasm and adenocarcinoma with peritoneal metastases.

Do not offer systemic chemotherapy routinely for low-grade appendiceal mucinous neoplasms or well-differentiated mucinous adenocarcinoma with peritoneal spread.

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Surgical interventions

Surgical resection: as per ASCRS 2025 guidelines, perform appendectomy if a grossly abnormal appendix is encountered during an unrelated abdominal operation.

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Follow-up and surveillance

Follow-up assessment: as per ASCRS 2025 guidelines, include the following in the surveillance after resection of appendiceal neuroendocrine tumors with a curative intent:

physical examination

serial biochemical testing

CT or MRI of the chest, abdomen and pelvis.

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