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Orthokeratinised Odontogenic Cyst — MFDS Part 1 MCQ

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HardOral PathologyOrthokeratinised Odontogenic CystMFDS Part 1

A 38-year-old man has a well-defined unilocular radiolucency associated with an unerupted mandibular third molar. Histological examination shows a thin, uniform epithelial lining with a prominent orthokeratinised luminal layer and granular cell layer. The basal cells are cuboidal or flattened without palisading. Compared with a conventional parakeratinised odontogenic keratocyst, which clinicopathological profile is most accurate?

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Correct answer: C — Low recurrence; no recognised association with nevoid basal cell carcinoma syndrome

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

This is an orthokeratinised odontogenic cyst (OOC), identified by orthokeratinisation, a prominent granular layer and cuboidal or flattened non-palisaded basal cells. Compared with a conventional parakeratinised odontogenic keratocyst, an OOC has lower epithelial proliferative activity, less aggressive biological behaviour and a substantially lower recurrence risk. It has no recognised association with nevoid basal cell carcinoma syndrome (Gorlin syndrome). Options B, D and E incorrectly assign the higher recurrence tendency of the conventional odontogenic keratocyst to the OOC. Options C, D and E also incorrectly imply a syndromic association. Palisaded hyperchromatic basal cells, often with nuclear polarisation, instead favour a conventional odontogenic keratocyst.

Reference: Li TJ, Kitano M, Chen XM et al. Orthokeratinized odontogenic cyst: a clinicopathological and immunocytochemical study of 15 cases. Histopathology. 1998;32:242–251. https://pubmed.ncbi.nlm.nih.gov/9568510/