Appendiceal mucocoele

Radswiki et al.

Appendiceal mucocoeles occur when there is abnormal accumulation of mucus within the appendix. The tenacious and viscous mucus causes obstruction of the appendiceal neck and results in dilatation of the lumen.

The reported prevalence at appendectomy is 0.2-0.3%. They are thought to typically present in middle aged individuals.

The term mucocele is simply a macroscopic description of an appendix that is grossly distended by mucus 7. They result from chronic appendiceal obstruction that may be caused by either benign or malignant lesions:

Variants
  • myxoglobulosis: seen as with multiple small intraluminal globules which can calcify and produce 1-10 mm mobile calcifications
Fluoroscopy: barium enema

If a contrast examination is performed, there is usually non-filling or partial-filling of the appendix. Where there is a large mucocoele, the associated mass effect can cause indentation or lateral displacement of the caecum.

Ultrasound

Typically cystic mass with variable internal echogenicity 8. The presence of an "onion sign" (sonographic layering within a cystic mass) is considered a highly suggestive feature 2,6.

CT
  • typically seen as a well-circumscribed, low-attenuation, spherical or tubular mass contiguous with the base of the caecum
  • the finding of curvilinear mural calcification suggests the diagnosis, but is seen in less than 50% of cases 
  • intra-luminal bubbles of gas, or an air-fluid level within a mucocele suggest the presence of superinfection, which can occur in both benign and malignant mucocoeles
MRI

Seen as a rounded right iliac fossa mass.

Typical signal characteristics include:

  • T1: depending on the mucin concentration, the signal may be variably hypointense to isointense 9
  • T2: hyperintense

Treatment is usually surgical.

Complications

Differentiating benign (non-neoplastic mucocoele and mucinous cystadenoma) and malignant (mucinous cystadenocarcinoma) appendiceal lesions can be difficult. Wang et al 10 found a statistically significant difference in wall irregularity and soft-tissue thickening between malignant and benign cases. 


Share article

Article Information

rID: 12273
Section: Pathology
Synonyms or Alternate Spellings:
  • Mucocoele of the appendix
  • Appendiceal mucocele
  • Appendicular mucocoele
  • Appendicular mucocele
  • Appendicocoele
  • Appendicocele
  • Mucocoele of appendix
  • Mucocele of appendix
  • Mucocele of the appendix
  • Appendiceal mucocoeles
  • Appendiceal mucoceles

Support Radiopaedia and see fewer ads

Cases and Figures

  • Drag
    Case 1: intra-operative photograph
    Drag here to reorder.
  • Drag
    Case 2
    Drag here to reorder.
  • Drag
    Case 3
    Drag here to reorder.
  • Drag
    Case 4: with onion sign - presumed mucocele
    Drag here to reorder.
  • Drag
    Case 5
    Drag here to reorder.
  • Drag
    Case 6
    Drag here to reorder.
  • Drag
    Case 7: due to adjacent caecal tumour
    Drag here to reorder.
  • Drag
    Case 8
    Drag here to reorder.
  • Drag
    Case 9
    Drag here to reorder.
  • Drag
     well-circumscrib...
    Case 10
    Drag here to reorder.
  • Drag
    Case 11
    Drag here to reorder.
  • Drag
    Case 12
    Drag here to reorder.
  • Drag
    Case 13
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.