Orthokeratinized odontogenic cyst (OOC): Clinicopathological and radiological features of a series of 48 cases.

OBJECTIVES:To demonstrate the clinicopathological and radiological features of orthokeratinized odontogenic cysts (OOCs), and analyze the epithelial cell proliferative activity between OOCs and odontogenic keratocysts (OKCs). MATERIALS AND METHODS:Clinicopathological and radiological analyses were performed in all OOC cases. The expression of cell proliferation markers, Ki-67 and cyclin D1, was detected by immunohistochemistry. RESULTS:A total of 48 OOC patients, 28 males and 20 females, were included. The mean age was 33.50 years, with a range of 13-61 years. The mandible was affected five times as frequently as the maxilla (mandible 40, maxilla 8). All OOCs were unilocular radiolucencies with well-defined margins, and 30 of 36 showed loss of continuity of the buccal or lingual cortices based on computed tomography (CT) images. Three cases exhibited root resorption; tooth displacement occurred in 4 cases. The average volume of the cysts on CT was 7794.25 ± 6952.98 mm3. All cysts were treated by enucleation or enucleation after decompression. The average follow-up time was 32.50 ± 27.58 months (ranging from 6 to 65 months), and the overall recurrence rate was 4.44% (2 of 45). Compared with OKCs, Ki-67 and cyclin D1 expression were significantly lower in OOCs (P < 0.001). CONCLUSIONS:OOCs occur more frequently in mandible with a slight male predilection and have a lower proliferative activity than OKCs. Radiologically, OOCs are more likely associated with buccolingual expansion and destruction of cortical bone. Due to the lower aggressiveness and recurrence rate, enucleation or decompression combined with enucleation is the first treatment choice for OOC.