LAUSR

Objective Melanocytes are widely distributed in the skin and often in oral mucosa but normally do not exist in bone tissue. The aim of this study was to compare the existence of melanocytes in odontogenic keratocysts (OKCs) and radicular cysts (RCs) and to clarify the difference in origin between those cysts. Methods One hundred and ten cases of OKCs and RCs were used. In OKC, 88 cases showed sporadic type (SPO), and 22 cases involved basal cell nevus syndrome (BCNS). OKC samples were divided into 54 cases in the juvenile group (0-29 years old) and 56 cases in the advanced group (30-70 years old). We researched these cysts with Melan-A and HMB45 immunohistochemical and Schmorl's reaction staining. Melanocytes were detected using Melan-A and HMB45 immunohistochemical stainings, and melanin pigmentation was detected using Schmorl's method. Results Melanocytes and melanin pigmentation were shown in OKC, and neither melanin pigmentation nor melanocytes existed in RC. The positive rate of Schmorl's reaction, Melan-A, and HMB45 staining were significantly higher in the juvenile group than in the advanced group. These rates were also higher in BCNS than in SPO. Conclusions Our data raise the important possibility that the origin of OKC epithelium differs from RC by the expression of melanocytes and melanin pigmentation. Our findings also underscore the fact that the origin of OKC differs between younger and older patients. It is suggested that melanin pigmentation and melanocytes expression may assist in the classification of odontogenic cysts in the future.