Epithelial Cell Proliferation in Odontogenic Keratocysts: a Comparative Immunocytochemical Study of Ki67 in Simple, Recurrent and Basal Cell Naevus Syndrome (BCNS)-associated Lesions

The aim of the present study was to investigate epithelial cell proliferation in the linings of odontogenic cysts, including three different subtypes of odontogenic keratocyst (OKC), namely simple (non-recurrent), recurrent and basal cell naevus syndrome (BCNS)-associated lesions. Ki67 immunoreactivity in OKC (simple, n = 10; recurrent, n = 8; syndrome, n = 9), dentigerous cysts (DC, n = 5), radicular cysts (RC, n = 5) and normal oral mucosa (n = 7) was studied using a biotin-streptavidin-peroxidase method on paraffin sections after microwave treatment. Ki67+ epithelial cells were counted manually and related to the length of basement membrane (BM) as determined by TV image analysis. Data were analysed by the Mann-Whitney U test. The number of Ki67+ cells in simple OKC linings (53.1 +/- 17.8 cells/mmBM) was similar to that in oral epithelium (42.5 +/- 12.7 cells/mmBM; P > 0.2). However, both contained significantly more Ki67+ cells than DC (3.9 +/- 1.3 cells/mmBM) and RC linings (6.7 +/- 4.8 cells/mmBM; P < 0.006). The epithelial distribution of Ki67+ cells differed between groups, with the percentage of positive cells in basal layers in OKC linings (7.0 +/- 2.1%) being significantly lower than that of oral epithelia (35.9 +/- 5.6%), DC (78.4 +/- 8.4%) and RC (80.6 +/- 7.7%) linings respectively (P < 0.003). Comparison of Ki67 expression within the OKC group revealed no significant difference between simple and recurrent lesions (44.0 +/- 13.8 cells/mmBM; P > 0.3). However, OKC associated with BCNS contained significantly higher numbers of Ki67+ cells (91.8 +/- 35.6 cells/mmBM; P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)