Peripheral odontogenic keratocyst associated with nevoid basal cell carcinoma syndrome: a case report

Abstract

Peripheral odontogenic keratocyst (POKC) is a rare gingival cyst showing histologic features identical to those of keratocystic odontogenic tumor. A rare case of POKC associated with nevoid basal cell carcinoma syndrome (NBCCS) is presented. A 24-year-old woman with NBCCS presented with a pigmented papule, 3 mm in size, involving the lingual gingiva of the right canine area of the mandible. Based on a clinical diagnosis of benign pigmentation, an excisional biopsy was performed, and a histopathologic diagnosis of POKC was rendered. The lining cells were positive for the proteins GLI2, BCL2, keratin 8, keratin 17, and mTOR. TP53 and Ber-EP4 were also weakly positive. Gene mutational analysis on a buccal swab sample revealed 2 missense mutations in the PTCH1 gene. This case is a distinctive example of a genuine soft tissue counterpart of keratocystic odontogenic tumor, in which an aberrant PTCH1-GLI pathway played a considerable role in the pathogenesis.