A case of an odontogenic keratocyst forming within a short period.

Odontogenic keratocyst is histologically and clinically distinct from other odontogenic cysts, especially with regard to its high recurrence rate and the remarkable growth capacity.We report a case of a 19-year-old man with an odontogenic keratocyst of the mandible. Radiographic findings showed that a cyst measuring 50×30mm developed during 1 year 6 months, and the growth rate was about 33mm per year.Proliferating cell nuclear antigen (PCNA) expression was also analyzed. Histopathologically, the cyst was lined by a relatively thick layer of parakeratinized epithelium, and partially deep prolongation of the epithelium was observed. A daughter cyst was not present.Immunohistochemically, staining using monoclonal antibody to PCNA revealed that the percentage of PCNA-positive cells in the odontogenic keratocyst lining (11.2%) was about twice that in the normal gingiva (4.6%). In the odontogenic karatocyst lining, PCNApositive cells were more often found in prickle cells than in basal cells.At present, there are no signs of recurrence as of 1 year 6 months after operation.