A Unique Case of Low-Grade Mucinous Neoplasm in Stump Appendectomy

An Incidental Finding of Low-Grade Appendiceal Mucinous Neoplasm in a Case of Borderline Brenner Tumor of the Ovary

The concurrent presentation of a low-grade appendiceal mucinous neoplasm (LAMN) and a borderline Brenner tumor (BT) of the ovary are exceedingly rare. Brenner tumors stand out as a particularly uncommon form, making up only around 5% of all benign epithelial tumors of the ovary. Among the ovarian Brenner, the borderline subtype is even rarer. Appendiceal neoplasm (LAMN) and right ovarian BT cannot be distinguished due to their anatomical position. LAMN is often an incidental finding and at later stages when left undiagnosed may lead to pseudomyxoma peritonei (PMP). This case describes a postmenopausal woman in her 50s experiencing abdominal pain and bloating for a week. Elevated carcinoembryonic antigen (CEA) levels and imaging suggested a potential right ovarian tumor. Interestingly, it revealed a unique combination of borderline Brenner tumor of the right ovary and low-grade appendiceal mucinous neoplasm.

Asymptomatic low-grade appendiceal mucinous neoplasm: A case report

BACKGROUND

Low-grade appendiceal neoplasms (LAMN) are characterized by low incidence and atypical clinical presentations, often leading to misdiagnosis as acute or chronic appendicitis before surgery. The primary diagnostic tool for LAMN is abdominal computed tomography (CT) imaging. Surgical resection remains the cornerstone of LAMN management, necessitating en bloc tumor excision to minimize the risk of iatrogenic rupture. Laparoscopy, known for its minimal invasiveness, reduced postoperative discomfort, and expedited recovery, is a safe and reliable approach for LAMN treatment. Despite the possibility of pseudomyxoma peritonei development, appendectomy and partial appendectomy generally result in negative tumor margins and favorable outcomes, which can be attributed to the disease's slow growth and lower malignancy.

CASE SUMMARY

A 71-year-old male patient was admitted to our hospital with a pelvic space-occupying lesion detected 1 mo prior. Physical examination showed a soft abdomen without tenderness or rebound and no palpable masses. No shifting dullness was noted, and digital rectal examination revealed no palpable mass. Enteroscopy revealed a raised, smooth-surfaced mass measuring 3.0 cm in the cecum. Abdominal contrast-enhanced CT showed a markedly thickened and dilated appendix with visible cystic shadows. Laparoscopic surgery was performed and revealed a significantly dilated appendix, leading to laparoscopic resection of the appendix and part of the cecum. Post-surgical pathologic analysis confirmed LAMN. The patient received symptomatic and supportive post-operative care and was discharged on postoperative day 4 without complications such as abdominal bleeding, intestinal obstruction, or incision infection. No tumor recurrence was observed during a 7-mo follow-up period.

CONCLUSION

LAMN is a rare disease that lacks specific clinical manifestations. Abdominal CT plays a crucial role in diagnosing LAMN, and laparoscopic surgery is a safe and effective diagnostic and therapeutic approach.