Orthokeratinized Odontogenic Cyst: An Unusual Histopathological Presentation

The orthokeratinized odontogenic cyst (OOC) is an uncommon developmental cyst that occurs between the second to fifth decades, more commonly in males. It is a solitary lesion that mostly occurs in the mandible rather than the maxilla. Histologic features include a thin, uniform epithelial lining with orthokeratinization and a prominent granular layer below a non-corrugated onion-skin-like surface.
A 40-year-old man presented with pain and swelling in the left mandibular canine molar area. The panoramic radiograph revealed a well-defined radiolucency extending from the left mandibular canine to the left mandibular molar, with scalloped projections between the teeth roots. Microscopic examination showed a cystic lesion lined by an orthokeratinized stratified squamous epithelium, and a prominent granular layer beneath the cornified layer was seen. The features were those of an OCC.
From the demographic and radiographic perspectives, the features of OOCs can be similar, but more variation can be found on routine histopathological analyses.