Man with abdominal discomfort.

Contributed from the case records of the  Indiana University Department of Radiology

Man with abdominal discomfort.

Man with abdominal discomfort.

• Mucocele of the appendix
• Acute appendicitis (abscess)
• Cecal carcinoma
• Appendiceal tumor (carcinoma or lymphoma)

Man with abdominal discomfort.

• Chronic cystic dilatation of appendiceal lumen by mucin accumulation
  • Rare
  • Mean age 50s
  • More common in female (4:1)
• Etiology
  • Any obstruction lesion can cause mucocele formation
  • Scarring (post appendicitis) is most common
  • Other causes: fecalith, appendiceal or cecal carcinoma, endometrioma, carcinoid, polyp, volvulus
• Classification
  • Based on histology:
    • Focal or diffuse mucosal hyperplasia (Simple or retention mucocele)
    • Mucinous cystadenoma (benign neoplasm, most common type of mucocele)
    • Mucinous cystadenocarcinoma (less common than cystadenoma, increased risk of perforation)
• Presentation
  • Asymptomatic, RLQ tenderness, palpable mass
  • Complications: rupture, torsion, intussusception
  • Pseudomyxoma peritonei: due to rupture (more common with malignant mucocele), peritoneal cavity filled with mucus seedings
• CT findings
  • Simple mucocele and mucinous cystadenoma: well-defined thin walled RLQ cystic mass, with wall or luminal calcification
  • Mucinous cystadenocarcinoma: solid and cystic components, large irregular mass, thickened enhancing nodular walls, calcifications in solid component
  • Pseudomyxoma peritonei: loculated ascites, scalloped surface of liver and spleen
• MR findings
  • Mucocele with increased fluid content is T1 hypo intense and T2 hyper intense
  • Mucocele with increased mucin content is T1 and T2 hyper intense
• Prognosis/treatment
  • Good prognosis for mucocele and cystadenoma
  • Poor prognosis for cystadenocarcinoma and for Pseudomyxoma peritonei
  • Surgical resection (right hemicolectomy)

1. Madwed D et al. Mucocele of the Appendix: Imaging Findings. AJR 159(1): 69-72, 1992.
2. Federle, M. D. Mucocele of the Appendix. Statdx.com. accessed 9/2011.

Man with abdominal discomfort.