Low-grade appendiceal mucinous neoplasm associated with ulcerative colitis: A case report and literature review.

RATIONALE

Colorectal cancer (CRC) development is a critical prognostic factor for patients with ulcerative colitis (UC), making its early detection important. However, early detection of CRC is clinically challenging. This case report describes a patient diagnosed with transverse colon cancer and a low-grade appendiceal mucinous neoplasm (LAMN) in the context of pancolitis-type UC.

PATIENT CONCERNS

A 59-year-old male patient with a 24-year history of pancolitis-type UC was referred to our hospital after a routine surveillance colonoscopy for the first time in 5 years revealed transverse colon cancer.

DIAGNOSES

Colonoscopy revealed type 3 advanced carcinoma in the transverse colon and a protruding lesion resembling a laterally spreading granular tumor at the appendiceal orifice. Computed tomography demonstrated enlargement of the appendix.

INTERVENTIONS

The patient underwent laparoscopic total colectomy, lymph node dissection of transverse colon cancer, ileal pouch-anal anastomosis, and temporary ileostomy.

OUTCOMES

The patient was diagnosed with stage IIA transverse colon cancer. Additionally, the appendiceal lesion was diagnosed as a LAMN, a relatively novel pathological entity considered a precursor to appendiceal mucinous adenocarcinoma.

LESSONS

Although the appendix is part of the colon and can serve as a site for UC-CRC development in patients with pancolitis-type UC, identifying appendiceal lesions through routine surveillance comprising colonoscopy alone may be challenging. In patients with pancolitis-type UC, lesions known as LAMN, which are recognized as precursors of appendiceal mucinous adenocarcinoma, may develop, thereby requiring careful monitoring.