A Rare Case of Low-grade Appendiceal Mucinous Neoplasm: A Case Report

Abstract

Low-grade appendiceal mucinous neoplasm (LAMN) is a rare malignancy with symptoms varying depending on the clinical manifestations. The most worrisome complication of this particular neoplasm is seeding of mucin into the adjacent peritoneum leading to pseudomyxoma peritonei (PMP). There is a lack of standardized treatment approach; however, an appendectomy-only approach is currently being used for the resection of non-metastatic disease. We present an unusual case of a 67-year-old male found to have LAMN status post elective appendectomy, six months after being treated for an appendiceal abscess.

Keywords: appendix; low-grade appendiceal mucinous neoplasm; mucin; pseudomyxoma peritonei.

Figure 1. CT scan of the abdomen/pelvis showing perforated acute appendicitis with a 7-cm abscess and large phlegmonous change (yellow arrow) in the right lower quadrant with secondary inflammatory changes

CT: computed tomography

Figure 2. CT scan of the abdomen/pelvis showing mass measuring 3 cm at the tip of the appendix (yellow arrow), with the absence of collection

Findings suspicious for post-inflammatory changes within the area; however, malignancy cannot be excluded. CT: computed tomography

Figure 3. Hematoxylin and eosin stain showing diffuse necrosis with invasive mucinous adenocarcinoma exhibiting extensive mural replacement by large, irregular, dissecting pools of mucin (red arrows), containing free-floating neoplastic epithelium