A distended, fluid-filled appendix over 1.5 cm with a thin or calcified wall and no fat stranding is a mucocele; its danger is rupture and pseudomyxoma peritonei, so the peritoneum is reported every time.
Orient first
- "Mucocele" is descriptive; most are low-grade appendiceal mucinous neoplasms (LAMN).
- Wall nodularity or soft tissue raises concern for mucinous adenocarcinoma.
- Rupture spreads mucin through the peritoneum (pseudomyxoma) — scalloping of the liver and spleen surface.
Acquire the study
- CT abdomen and pelvis in portal venous phase with coronal reformats.
The manoeuvre
- Appendix diameter in cm on axial and coronal reformats — over 1.5 cm with low-attenuation contents suggests mucocele.
- Wall: thin, curvilinear calcification, or enhancing nodules (measure in mm).
- Periappendiceal fat: stranding favours appendicitis; its absence favours mucocele.
- Peritoneum: low-attenuation ascites, scalloping of the liver and spleen surface, omental disease.
What confirms it
- Histology of the resected appendix; imaging states "appendiceal mucocele, likely mucinous neoplasm" with the peritoneal findings.
What licenses you to exclude it
- A normal-calibre appendix excludes a mucocele; a periappendiceal abscess can hide a ruptured one.
The classic misread
- Calling it acute appendicitis and prompting a rupture-prone appendicectomy without an oncological plan.
- Missing early pseudomyxoma — look at the liver surface.