A case of squamous cell carcinoma arising from an inverted papilloma on the tongue

Abstract

　Many cases of papillomas on the tongue have been reported. Clinically, resection is often recommended because of the possibility of canceration. However, the pathology of the canceration process and the mechanism of cancer development have not been clarified. For sinonasal papillomas, a consensus regarding the grading of dysplasia in inverted papillomas does not yet exist, and the diagnosis of malignant transformation can be challenging. The patient was a 48-year-old woman. A tumor on her tongue was detected, and fiberscopic examination using narrow-band imaging showed a papillary structure and relatively organized new blood vessels. A biopsy revealed an inverted papilloma, and surgery was planned because of the possibility of canceration. A partial glossectomy was performed. Microscopic evaluation of the surgical specimen showed hyperplasia and multiple invasions of the surface epithelium into the underlying stroma, composed of squamous cells. Immunohistochemical staining showed the focal expression of p53, and p16 was negative. In addition, BerEP4 and EGFR were partial positive. By evaluating p53 staining images at the same site as HE staining, in this papilloma it was possible to confirm the site showing canceration and the site not so. Consequently, a pathological diagnosis of squamous cell carcinoma arising from an inverted papilloma on the tongue was made.