Radicular Cyst — ORE Part 1 MCQ

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ModerateOral PathologyRadicular CystORE Part 1

A patient presents with a periapical radiolucency around the apex of a non-vital lower premolar. The radiolucency is well-defined and approximately 15 mm in diameter. Aspiration yields straw-coloured fluid. What is the most likely diagnosis?

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Correct answer: D — Radicular cyst

Explanation lettering: C = shown as A · D = shown as B · B = shown as C · A = shown as D

The diagnosis is radicular cyst (A). The key discriminators are the well-defined radiographic appearance, the ability to aspirate fluid, and the straw-coloured character of that fluid. Radicular cysts are epithelium-lined cavities that form from epithelial cell rests of Malassez in response to pulpal necrosis and periapical inflammation. They accumulate clear, osmotically-driven serous fluid, which appears straw-coloured on aspiration. Periapical granulomas (B) are composed of granulation tissue and do not yield fluid; aspiration yields only tissue. Periapical abscess (C) would present with purulent or blood-stained aspirate and radiographically ill-defined margins. Lateral periodontal cyst (D) occurs on vital teeth and would not be associated with a non-vital apex. Odontogenic keratocyst (E) is a developmental lesion not associated with non-vital teeth and does not present as a periapical finding.

Reference: Comparative Evaluation of Digital Radiography and Ultrasound Imaging to Detect Periapical Lesions in the Oral Cavity. NCBI PMC, 2023. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9639700/