Mucinous Adenocarcinoma of the Appendix: A Deep-Seated Tumor

Abstract

Primary tumors of the appendix are rare and approximately 85% are carcinoids. Primary adenocarcinoma of the appendix accounts for about 0.2% of all gastrointestinal neoplasms, only 6% of appendiceal cancers, 0.05%-0.2% of all appendectomy specimens, and have an age-adjusted incidence of 0.12 cases per 1,000,000 patients per year. Appendiceal adenocarcinoma is categorized into colonic, mucinous, goblet cell, and signet ring cell subtypes. We present a 72-year-old male with a past medical history of diabetes mellitus and benign prostatic hyperplasia with complaints of abdominal pain for two days. The pain was located in the left upper and lower quadrants, characterized as spastic and lasting for a few minutes at a time. An abdominal computed tomography (CT) scan showed severe loss of serosal margins about the cecum extending posteriorly through the peritoneal lining of the right paracolic gutter. A mass with a diameter of 3.8 x 3.3 cm was identified along the base of the cecum extending cephalic to the inferior edge of the ileocecal junction. The appendix was not identifiable. Diagnostic colonoscopy failed to identify any cecal mass and the appendiceal orifice appeared normal. Biopsies from the cecum were unremarkable. The patient was referred for surgical consultation with subsequent exploratory laparoscopy identifying a large hard fixed appendiceal mass measuring 5.5 x 3.5 x 3.5 cm. The mass was resected and a right hemicolectomy with side-to-side anastomosis performed. Surgical pathology revealed moderately differentiated mucinous adenocarcinoma of the appendix extending to the cecal subserosal fat; TNM staging T3N0M0, Grade 2, Stage IIa. Mucinous adenocarcinoma (MA) usually presents with nonspecific findings. Abdominal pain is the most frequently cited symptom, resembling acute appendicitis. However, MA can present as an abdominal mass detected by palpation or abdominal imaging, and rarely with nausea, vomiting, ascites, or unintentional weight loss. As a result of its nonspecific presentation, it is rarely diagnosed preoperatively. Furthermore, appendiceal cancers are commonly missed during colonoscopy as the cancer is located deep in the appendix and not visible from the cecal lumen. These tumors are found during exploratory surgery, similar to our case. Although rare, appendiceal tumors should be part of the differential diagnosis when a history of abdominal pain and a cecal or appendiceal mass is seen on CT scan despite a negative colonoscopy.1467 Figure 1. (Above) Abdominal computed tomography (CT) scan showed severe loss of serosal margins about the cecum, extending posteriorly through the peritoneal lining of the right paracolic gutter. A mass was identified along the base of the cecum, with a diameter of 3.8 x 3.3 cm, extending cephalic to the inferior edge of the ileocecal junction. The appendix was not identifiable as a discrete structure. (Below) Diagnostic colonoscopy was unable to identify any intestinal masses extending into the lumen.