Lateral Periodontal Cyst — ORE Part 1 MCQ

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ModerateOral PathologyLateral Periodontal CystORE Part 1

A patient presents with a well-defined, round radiolucency in the mandibular premolar region between the roots of two vital teeth. It is approximately 8 mm in diameter and has a thin corticated border. There is no associated tooth pathology. What is the most likely diagnosis?

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Correct answer: E — Lateral periodontal cyst

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

Lateral periodontal cyst (LPC) is the correct answer. The diagnostic constellation is definitive: (1) radiolucency located between the roots of VITAL teeth (ruling out radicular cyst and periapical granuloma, both of which require pulp necrosis), (2) small size <1 cm, (3) round well-circumscribed morphology, (4) thin corticated border (sclerotic margin), and (5) mandibular premolar region (classic LPC location). LPC is an uncommon, non-inflammatory developmental cyst representing 0.4–0.7% of odontogenic cysts. Radicular cyst (B) and periapical granuloma (C) are ruled out by the vital status of adjacent teeth. Odontogenic keratocyst (D) is keratinised and typically presents differently. Stafne bone cavity (E) is an anatomical defect unrelated to tooth roots. Histopathological examination would confirm the diagnosis, showing non-keratinised epithelium with glycogen-rich clear cells and epithelial plaques.

Reference: Multiple sources: Buchholzer S, et al. Atypical presentation of lateral periodontal cyst associated with impacted teeth. BMC Oral Health. 2021; 21:257. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8028169/ and Chaudhuri P, et al. Lateral periodontal cyst of the anterior maxilla: a rare case report. BMC Oral Health. 2025. https://pubmed.ncbi.nlm.nih.gov/40336026/