Low-grade appendiceal mucinous neoplasm at appendiceal orifice treated via appendectomy with double purse-string suture method: A case report

Abstract

BACKGROUND

Low-grade appendiceal mucinous neoplasms (LAMNs) are a class of histologically well-differentiated adenomas that can proliferate outside the appendix in the form of malignant tumours, resulting in the accumulation of external appendiceal mucus. They may present as an extra-appendiceal mass-like bulge, mucus or polypoid tissue at the appendiceal orifice, or even with abdominal dissemination. The surgical approach is usually appendectomy, ileocecal resection or right hemicolectomy. It is essential to raise awareness of LAMNs and choose an appropriate treatment.

CASE SUMMARY

A 68-year-old man underwent a routine physical examination at our hospital on May 17, 2022. The patient had no symptoms of abdominal pain, bloating, or weight loss, and his tumour marker levels were normal. The faecal occult blood test was negative, and no abnormalities were identified on physical examination. Colonoscopy revealed a submucosal protrusion at the appendiceal orifice. During endoscopic ultrasound, uneven echoes were observed in the appendix cavity. A contrast-enhanced computed tomography scan of the abdomen revealed a nodular thickening at the base of the appendix, with a diameter of approximately 1 cm. When all the examination results were considered, we suspected the lesion to be an appendiceal mucinous tumour. Laparoscopic surgery was performed using the double purse-string suture method. Postoperative pathology suggested a low-grade mucinous cystadenoma of the appendix with no involvement of the margins. A repeat colonoscopy 18 months after surgery revealed no significant abnormality at the appendiceal orifice. A contrast-enhanced computed tomography scan of the abdomen suggested only postoperative changes.

CONCLUSION

This study describes a case of LAMN that was treated by resecting the mass at the appendiceal orifice via the double purse-string suture technique and provides new insights on the diagnosis and treatment of LAMNs.

Key Words: Appendiceal orifice mass; Low-grade appendiceal mucinous neoplasm; Double purse-string suture; Surgical approach; Treatment; Case report

Core Tip: Low-grade appendiceal mucinous neoplasms are a class of histologically well-differentiated adenomas. For low-grade appendiceal mucinous neoplasms with mass formation at the appendiceal orifice, if no metastatic lesion is indicated by imaging, the appendix and the mass at the appendiceal orifice should be completely resected. Our technique mainly targeted a mass approximately 1 cm from the opening of the appendix. We made the first pouch 1 cm from the root of the appendix, thus ensuring the anatomical integrity of the ileocecal valve. If conventional cutting closure is used, the anatomy of the ileocecal flap may be destroyed.

INTRODUCTION

Compared with other gastrointestinal tract tumours, appendiceal neoplasms are rare, but their incidence is increasing[1]. The choice of treatment for low-grade appendiceal mucinous neoplasms (LAMNs) in the absence of appendiceal perforation and abdominal metastatic lesions is to ensure that the surgery can completely remove the appendix and the mass. In patients with LAMNs presenting as appendiceal orifice masses, a simple appendectomy does not ensure complete removal of the mass and may even result in medically induced abdominal dissemination. In patients with an appendiceal orifice mass of 1 cm or less, a double purse-string suture can be used to ensure complete resection.

CASE PRESENTATION

Chief complaints

The patient has no body uncomfortable, requested a colonoscopy.

History of present illness

The patient had no symptoms of abdominal pain, bloating, or weight loss.

History of past illness

The patient denied a history of hypertension, diabetes, hepatitis, tuberculosis, and trauma.

Personal and family history

The patient had no personal or family history of tumours.

Physical examination

Physical examination was negative.

Laboratory examinations

The tumour markers of the patient were normal. Faecal occult blood test was negative.

Imaging examinations

Colonoscopy revealed a submucosal protrusion at the opening of the appendix (Figure 1A). During endoscopic ultrasound, uneven echoes were observed in the appendix cavity (Figure 1B). A contrast-enhanced computed tomography (CT) scan of the abdomen revealed a nodular thickening at the base of the appendix, with a diameter of approximately 1 cm (Figure 1C).

Figure 1 Clinical data of the patient with a low-grade appendiceal mucinous neoplasm at the appendiceal orifice. A: Normal colonoscopy showed a submucosal protrusion at the appendiceal orifice; B: Ultrasound colonoscopy image; C: Abdominal computed tomography enhancement; D: Pathology suggested a low-grade mucinous cystadenoma of the appendix with no involvement of the margins; E: Repeat colonoscopy 18 months after surgery revealed no significant abnormality at the appendiceal orifice; F: Computed tomography enhancement of the abdomen suggested postoperative changes in the appendix.

FINAL DIAGNOSIS

Postoperative pathology revealed a low-grade mucinous cystadenoma of the appendix with no involvement of the margins (Figure 1D).

TREATMENT

Before surgery, we communicated with the patient’s family regarding the surgical methods, including the double purse-bag method and the double purse-bag method. Due to the cost of surgery, the patient’s family chose the double purse-bag method. Laparoscopic surgery was performed on May 21, 2022. The patient received bowel preparation prior to the planned surgery. Absorbable surgical sutures, model 3-0, were used throughout surgery. During the operation, we did not find any surface mucin or mucin in the right iliac fossa or Morrison’s pouch. The double purse-string suture technique was performed by creating a purse-string suture approximately 1.0 cm below the swelling, at the appendiceal orifice. The incision was made 0.5 cm from the ligature line, and the appendix and swelling at the orifice were completely excised (Figure 2A and B), and a second purse-string suture was performed 1.0 cm from the ligature line, with the remaining end embedded and sutured into the purse (Figure 2C and D).

Figure 2 Double purse-string suture technique. A: A purse-string suture was created approximately 1.0 cm below the swelling; B: A cut was made 0.5 cm from the ligature line; C: A second purse-string suture was performed 1.0 cm from the ligature line; D: The remaining end was embedded into the purse-string suture.

OUTCOME AND FOLLOW-UP

The patient recovered well after surgery. A repeat colonoscopy 18 months after surgery revealed no significant abnormality at the appendiceal orifice (Figure 1E). A contrast-enhanced CT scan of the abdomen suggested only postoperative changes (Figure 1F).

DISCUSSION

The World Health Organization classifies the majority of non-invasive tumours of epithelial origin as LAMNs, which are essentially a histologically well-differentiated type of adenoma. However, they can proliferate outside the appendix in a manner resembling the growth of malignant tumours, leading to the accumulation of mucus outside the appendix. In contrast, high-grade appendiceal mucinous neoplasms present a greater degree of cellular atypia than LAMNs, indicating their more aggressive nature[2,3]. Appendiceal neoplasms can cause appendix perforation and abdominal dissemination. When peritoneal dissemination produces large amounts of mucus, it is defined as pseudomyxoma peritonei. Surgical treatment can be used for patients with low-grade or high-grade appendix neoplasms and peritoneal metastasis. In the absence of perforation of the appendix or involvement of the peritoneum, it is important to avoid perforation of the appendix and tumour implantation during the surgical process and to maintain the integrity of the resected tumour.

Most studies have shown that LAMNs that are confined to the appendix, without perforation or peritoneal metastasis, can be cured with a simple appendectomy, which has a low recurrence rate[4]. For LAMNs with mass formation at the appendiceal orifice, if no metastatic lesion is indicated by imaging, the appendix and the mass at the appendiceal orifice should be completely resected. Anatomically, the ileocecal valve is located 2.0-3.0 cm from the opening of the appendix, and our technique mainly targeted a mass approximately 1 cm from the opening of the appendix. We made the first pouch 1 cm from the root of the appendix, thus ensuring the anatomical integrity of the ileocecal valve. If a conventional cutting closure is used, the anatomy of the ileocecal flap may be destroyed. If only the appendix is resected, there is a high probability of positive resection margins. For patients with positive resection margins, some guidelines currently recommend additional procedures, such as a typhlectomy, ileocecal resection or right hemicolectomy[5,6].

CONCLUSION

In this case, the patient presented with a mass at the orifice of the appendix measuring approximately 1 cm. We opted for the double purse-string suture technique and successfully removed the appendix and the mass at the orifice of the appendix completely. Therefore, the double purse-string suture technique may be an effective and feasible surgical approach for LAMNs. The patient will be followed up for 10 years with annual abdominal/pelvic CT scans and tumour markers including carcinoembryonic antigen and cancer antigens 125 and 19-9. CA199 is a tumour marker that can be used to monitor tumour progression and recurrence.

ACKNOWLEDGEMENTS

The authors sincerely thank the participant for his willingness to participate in this study.