KEY FACTS
Terminology
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Distension of appendiceal lumen as result of mucin accumulation from epithelial proliferation or obstruction
Imaging
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Distended tubular or pear-shaped cystic structure in right lower quadrant with low-level internal echoes
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Connects with medial wall of cecal pole
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Presence of calcification in wall strongly supports diagnosis of appendicular mucocele
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Concentric layering of dense mucoid material gives onion skin appearance
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Fecalith or appendicolith may be visible in obstructive type
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Hypovascular
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Soft tissue thickening and irregularity of mucocele wall suggest malignancy
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Contrast-enhanced CT scan is best imaging modality for characterization and staging
Top Differential Diagnoses
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Appendiceal carcinoma or acute appendicitis
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Hydrosalpinx
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Cystic ovarian neoplasm
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Tuboovarian abscess
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Duplication cyst/mesenteric cyst
Pathology
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Benign > malignant
Clinical Issues
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Most commonly: Right lower quadrant pain/palpable mass
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Frequently discovered incidentally
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Preoperative differentiation of benign and malignant mucoceles challenging
Scanning Tips
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Transvaginal ultrasound improves image quality and helps to differentiate from ovarian cystic masses
in the right pelvis, containing echogenic mucoid material.
