Immunohistochemical Marker Expression in the Lateral Peridontal Cyst and its Variants

The lateral periodontal cyst (LPC), gingival cyst of the adult (GCA) and botryoid odontogenic cyst (BOC) are developmental odontogenic cysts. BOC is unique among the three because of its more aggressive behavior and higher recurrence rate. A pilot study by Redman et al (2017) evaluated a BOC, GCAs and LPCs using Ki-67, p53, BCL-2 and caspase-3 stains. The single BOC sample showed elevated BCL-2 and p53 levels when compared to the other variants. Objectives: This follow-up study evaluated if there were significant differences in proliferative activity and apoptosis of cells within the epithelial linings of GCA, LPC and BOC. Additionally, it explored Ki-67, p53, BCL2 and caspase-3 activity in a larger cohort of specimens. Methods: Archived formal infixed paraffin embedded tissue blocks of BOC (15 specimens), LPC (6 specimens), GCA(6 specimens) and 3 odontogenic keratocysts (OKCs) were prepared for immunohistochemical evaluation. Diagnoses of individual specimens were confirmed using hematoxylin and eosin. The specimens were then stained with Ki-67, p53, BCL2 and caspase-3. A labeling index (LI) was determined for each specimen by counting the number of positively labeled epithelial cells per 1000 epithelial cells. A mean LI +standard deviation (SD) was then established for each immunohistochemical marker and cyst type in order to perform statistical analysis (p<0.05). GCAs, LPCs and BOCs served as test samples and the three OKCs as control.