Hyalinizing clear cell carcinoma arising on the anterior palatoglossal arch

Hyalinizing clear cell carcinoma (HCCC) is very rare in the oral cavity, arising more frequently in the minor salivary glands. We present the case of a 57-year-old woman with a swelling on the anterior palatoglossal arch of 2x1 cm size. An incisional biopsy was taken and histological examination revealed typical clear cells arranged in anastomosing trabeculae, cords, nests, and solid sheets with a hyalinizing stroma. These clear cells were strongly positive to periodic acid-Schiff stain (PAS) but were negative for mucicarmine. Immunohistochemically, the neoplastic cells were immunoreactive to pancytokeratin, focally positive to EMA, but negative for smooth muscle actin (SMA), vimentin and S-100 protein, HMB45, CD68, carcinoembryonic antigen (CEA) and glial fibrillary acid protein (GFAP). These findings allowed us to define this tumor as a clear cell tumor of the anterior palatoglossal arch. The tumor was subjected to radical excision and the patient is doing well at twelve months after surgery. This report focuses on the heterogeneous group of clear cell neoplasms with the intent of pointing out some aspects that may contribute to forming a diagnosis of HCCC, and which, above all enable us to distinguish this neoplasm from other very similar forms occurring in the oral cavity.