17/08/2026
Lately, we have encountered some cases of orthokeratinized odontogenic cyst (OOC) that presented as surprisingly large lesions, with marked expansion and a clinically aggressive appearance.
Although OOC is generally considered an indolent odontogenic cyst with a favorable prognosis, larger lesions may occasionally show extensive expansion and multilocularity, creating a diagnostic challenge.
This highlights an important diagnostic pitfall: a large, expansile lesion with keratinized epithelium should not automatically be classified as an odontogenic keratocyst (OKC).
OOC is characterized by a mature orthokeratinized lining with a prominent granular cell layer, whereas OKC typically shows a parakeratinized, corrugated lining with palisaded basal cells. However, secondary inflammation or other epithelial changes may obscure these characteristic features and create areas of histologic overlap.
Careful evaluation of the entire epithelial lining, adequate sampling, and correlation with the clinical and radiographic findings are essential for an accurate diagnosis.