Papillary squamous cell carcinoma of the mandibular gingiva.

Papillary squamous cell carcinoma (PSCC) has rarely been reported in the oral cavity. Herein reported is a case of PSCC in the mandibular gum. A 70-year-old man consulted our hospital because of a papillary tumor in the left mandibular gum. Physical examination revealed an exophytic papillary tumor of the left mandibular gum, and an excision of the tumor was performed. Grossly, the tumor was exophytic and papillary, and measured 1 x 1 x 0.8 cm. Microscopically, the tumor showed exophytic papillary proliferation with fibrovascular cores and consisted of atypical squamous epithelial cells. The tumor cells showed hyperchromasia, nuclear atypia, mitotic figures, apoptotic bodies, cancer pearls, and individual keratinization. Mild stromal invasion was seen. Immunohistochemically, the tumor cells were positive for pancytokeratin AE1/3, pancytokeratin CAM5.2, p63, p53, and Ki-67 (labeling index=40%), but negative for human papilloma virus (HPV). HPV in situ hybridization revealed no signals. Therefore, PSCC was diagnosed. The lateral and vertical margins are negative for tumor cell. The pathological diagnosis was PSCC. The patient was healthy and free from tumor three months after the operation.