Acute appendicitis, inflammatory appendiceal mass and the risk of a hidden malignant tumor: a systematic review of the literature

Abstract

Introduction: Acute appendicitis is significantly common. Despite the increased use of computed tomography, the number of perforated cases has been stable in the past three decades. Between 2% and 6% of patients with acute appendicitis present appendiceal mass, often described as inflammatory phlegmon or abscess. Malignant tumors are confirmed by pathological analysis in 0.9-1.4% of all appendectomies performed to treat acute appendicitis. However, recent series demonstrate an elevated incidence of malignancies, ranging from 5.9 to 12%, in patients with inflammatory appendiceal mass.

Methods: The analysis was based on a systematic review of the literature. The articles were searched in PubMed for the period from 1987 to 2016. Articles presenting the incidence of the hidden malignancy among patients with appendiceal inflammatory mass were selected. Variables as age, interval appendectomy rate, the incidence of neoplasm, time to surgery, minimally invasive assessment, histology, right colectomy rate and morbidity were analyzed.

Results: A total of 13.244 patients were described as presenting acute appendicitis. Appendiceal tumor is present in approximately 1% of the appendectomies, while the rate of neoplasm varies from 10 to 29% in patients presenting appendiceal inflammatory mass. Interval appendectomies, despite been the minority of the procedures, disregard the higher morbidity associated with right sided colectomies. The review of literature also describes oncologic, histologic and clinical aspects of patients presenting appendiceal neoplasm, describing the most frequent histologic subtypes of this illness.

Conclusion: Hidden appendiceal neoplasm in acute appendicitis are rare, fortunately. However, its incidence is much higher in patients presenting appendiceal inflammatory mass. Hence, interval appendectomy should be considered in this subgroup of patients.

Keywords: Acute appendicits; Appendiceal inflammatory mass; Appendiceal neoplasms; Appendiceal neuroendocrine tumors; Interval appendectomy; Pseudomixoma peritonei.

Fig. 1

Diagram of study selection

Fig. 2

The number of appendix tumors, adjusted by age, from 1997 to 2007, according to SEER database (per 100,000 inhabitants)

Fig. 3

Survival according to the histological type. Modified by Turaga et cols, Ann SurgOncol (2012) 19:1379–1385

Fig. 4

Well-differentiated neuroendocrine neoplasia, with 1 to 2 cm, located in the tip of the appendix. Degree I (WHO) (Courtesy of Andre Bouzas, MD – Oncology Institute - Santa Paula Hospital, São Paulo

Fig. 5

Low-grade mucinous neoplasia (LAMN – Grade 1 WHO), measuring 2 cm, invading the distal third with free margin

Fig. 6

Surgical specimen from ileocolectomy to treat perforated appendiceal mucinous adenocarcinoma

Fig. 7

Dilated appendix, with a diameter of 3.5 cm compatible with appendiceal mucocele, in ultrasound

Fig. 8

Axial computerized tomography view of a burst cecal appendix (up to 3.5 cm), with thin and regular walls, and no signs of densification of adjacent adipose tissue. This corresponds to the cystic formation already described in the ultrasound, compatible with mucocele of undetermined etiology. Appendectomy revealed well-differentiated mucinous adenocarcinoma, with invasion into of the muscularis mucosae

Fig. 9

Axial computerized tomography view showing mucin lakes in a patient with low-grade appendiceal mucin adenocarcinoma limited to the right iliac fossa. Pathological analysis revealed extra-appendicular mucin without the presence of mucinous epithelium

Fig. 10

Intraoperative view of pericecal and retrocecal mucin. The disease was limited to the right iliac fossa. Pathological analysis analysis revealed no cells in the mucin

Fig. 11

PET-CT of a patient subjected to appendectomy to treat acute appendicitis with incidental diagnosis of appendiceal tubular adenocarcinoma with signet-ring cell formation T3NXMX. In postoperative follow-up, CEA was elevated and the PEC-CT revealed pericecal lymphadenopathy

Fig. 12

Product of ileocolectomy and/or right colectomy performed in same patient of Fig. 11, revealing pericecal lymphadenopathy. Margins in the caecum showed a 2.5 cm adenocarcinoma with signet-ring cell formation and metastasis in nine of the 14 dissected lymph nodes. pT3pN2