skip to main content

Lateral Periodontal Cyst — MFDS Part 1 MCQ

Instant feedback + full explanation. One question, done properly.

HardOral PathologyLateral Periodontal CystMFDS Part 1

A 56-year-old patient has an incidental 8 mm, well-corticated, unilocular radiolucency between the roots of a vital mandibular canine and first premolar. Histological examination shows a non-inflamed fibrous cyst wall lined predominantly by one to five layers of non-keratinising cuboidal-to-squamous epithelium. Focal plaque-like epithelial thickenings contain glycogen-rich clear cells. Which odontogenic cyst is the most likely diagnosis?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Lateral periodontal cyst

The diagnosis is a lateral periodontal cyst. The decisive combination is a small lateral radiolucency between vital teeth and a thin, non-keratinising epithelial lining with focal plaque-like thickenings and glycogen-rich clear cells. An odontogenic keratocyst has a keratinised, typically corrugated lining with basal palisading. A dentigerous cyst can have a thin non-keratinised lining, making the original stem ambiguous, but it is attached at the cervical region of an unerupted tooth and lacks the characteristic epithelial plaques. A radicular cyst is inflammatory and usually associated with a non-vital tooth. A calcifying odontogenic cyst contains ghost cells and may show calcification. These additional findings make option A uniquely defensible.

Reference: Koudelka et al., Atypical presentation of lateral periodontal cyst associated with impacted teeth: two case reports, 2021. https://pubmed.ncbi.nlm.nih.gov/33827538/