Mucocele of the Appendix: A Rare Disease

Abstract

Introduction: Mucocele of the appendix is caused by a retention cyst, mucosal hyperplasia, mucinous cystadenoma or mucinous cystadenocarcinoma. It is extremely rare, found in 0.2-0.3% of resected appendices in the United States. Early diagnosis is rare due to absent or nonspecific symptoms like right lower quadrant abdominal pain, gastrointestinal bleeding, intestinal obstruction, genitourinary symptoms or acute abdomen. Early diagnosis and resection are important since some appendiceal mucoceles are malignant and may lead to peritoneal dissemination and the clinical syndrome of pseudomyxoma peritonei. Case report: A 74-year-old male presented with intermittent right lower quadrant abdominal pain and hematochezia for 4-6 weeks. He had no pertinent abdominal symptoms including nausea, vomiting, bloating, diarrhea or constipation or weight loss. Routine laboratory testing showed microcytic anemia. He had a colonoscopy 5 years ago which was normal. Repeat colonoscopy showed a protuberant mass at appendiceal orifice which was firm on palpation with biopsy forceps. Biopsy of the lesion showed mild inflammatory changes. With the above described endoscopic appearance of the lesion, clinical suspicion for mucocele was high, hence CT scan was obtained. CT scan showed low attenuation, well-defined 2.5-cm mass, with no signs of inflammation suggestive of mucocele of the appendix. Patient underwent surgery for ileo-caecal resection. Histopathology of the surgical specimen was reported as mucinous cystadenoma of appendix. On 3-month follow-up, patient is doing well and his anemia is resolving. Discussion: Appendiceal mucoceles may be recognized at colonoscopy as an extrinsic or submucosal lesion with smooth indentation into the caecal lumen. Appearance of the appendiceal orifice in the center of the mound has been labeled as the “volcano sign.” Highly suggestive endoscopic finding is that of a glossy, rounded, balloon-shaped mass protruding from the appendiceal orifice and moving in and out with respiration. This case highlights the importance of endoscopic appearance of appendiceal mucocele which can be missed on a biopsy. Further imaging is warranted when mucocele of appendix is suspected on colonoscopy. Recognition at colonoscopy is important as it enables accurate diagnosis of this rare clinical entity. Surgical excision of the tumor without rupture is of paramount importance because rupture of the lesion causes pseudomyxoma peritonei. Survival is excellent after standard appendectomy of retention cysts, mucosal hyperplasia, or cystadenoma.