This report describes a case of odontogenic cyst with keratinization and dysplastic change of lining epithelium, which showed the manifestation of inflammatory radicular cyst, clinically. A 28-year-old man complained of dull pain in the right mandibular molar region. Radiographically a well-defined oval cystic lesion with non-vital teeth, a common finding in radicular cyst, was observed. Microscopically, the lining epithelium of the cyst demonstrated both keratinization and severe epithelial dysplasia. Atypical findings such as hyperchromatic nuclei, increase of N/C ratio and drop shaped rege ridge were observed in the lining epithelium. However, definite invasion into fibrous connective tissue was not found. Immunohistochemically, the dysplastic lining epithelium was highly positive for proliferative marker, Ki-67. Based on the dysplastic changes of lining epithelium, this periapical lesion would be considered to be signs of malignant change. From this case, we conclude that definitive diagnosis by microscopical examination should be made, even if the periapical lesion would be clinically considered as inflammatory radicular cyst.

The purpose of this study was to evaluate the role of EGF(Epidermal Growth Factor), EGFR(Epidermal Growth Factor Receptor), aFGF(acidic Fibroblast Growth Factor, FGF-1), bFGF(basic Fibroblast Growth Factor, FGF-2), FGFR(Fibroblast Growth Factor Receptor) in the development of radicular cyst. For this study 37 subjects, diagnosed as radicular cysts. referred to the Dept. of Oral Path. College of Dentistry, Kyung Hee University, were used as experimental group. And for control group, 2 subjects of normal oral epithelium without any inflammatory changes were used. All the tissues; experimental and control group were neutral formation fixed and paraffin embedded. serial tissue section were made at 5㎛ and processed in the standard way for immunohistochemical method, using primary antibodies against, EGF(Antirabbit Ig G at 1:100 dilution), EGFR(Antimouse Ig G at 1:100 dilution), aFGF(Antirabbit Ig G, rabbit kit at 1:100 dilution), bFGF(Antirabbit Ig G, mouse kit at 1:100 dilution), FGFR(Antimouse Ig G mouse kit at 1:100 dilution), all BioGenex U.S.A. made except EGFR(Chemicon U.S.A.) followed by the Streptavidin - Horse Radish Peroxidase (InnoGenex Human-avidin kit) application, counter stained with Meyer's hematoxylin stain method. And examined under microscope, graded 0(no epithelial stain), +(weak or focal epithelial stain), ++(moderate or focal intensive epithelial stain), +++(intense generalized epithelial staining) for the epithelium, and connective tissue of cyst wall. 1. EGF, EGFR, aFGF, bFGF, FGFR showed more intense staining on radicular cysts compare to that on the normal mucosa. 2. EGF, EGFR, aFGF, bFGF, FGFR stained in mucosa, submucosa of the control group and also stained on the lining epithelium, connective tissues of cyst wall in the experimental group. EGF, EGFR, aFGF, bFGF, FGFR take a part in the development of the radicular cyst.