Central hyalinizing clear cell carcinoma of the mandible and the maxilla a clinicopathologic study of two cases with an analysis of the literature.

We describe two cases of primary intraosseous hyalinizing clear cell carcinomas of the jaws. One tumor arose in the mandible, the other in the maxilla. Both patients were adult women. Histologically, both tumors were characterized by a population of clear, glycogen-rich cells arranged in solid nests, trabeculae, and occasional single files, surrounded by a markedly hyalinized fibrous stroma. In close admixture with the clear cells, a second component of smaller cells having eosinophilic cytoplasms was also noted. Focal areas of squamous metaplasia were seen in one of the tumors. Neither nuclear pleomorphism nor mitotic activity were conspicuous features. Mucicarmine stains were negative in both tumors. Immunohistochemically, the tumor cells expressed cytokeratins and epithelial membrane antigen. Stains for S100 protein, smooth muscle specific actin, and carcinoembryonic antigen were all negative. Both patients are alive and well 14 and 17 months respectively after the diagnosis without evidence of metastasis or recurrence. The major importance of recognizing the existence of this rare form of salivary gland-type adenocarcinoma arising as a primary lesion in the mandible or the maxilla lies in avoiding misdiagnosing it as other primary or metastatic clear cell neoplasms, including various odontogenic clear cell tumors, other primary intraosseous salivary gland tumors, and metastatic clear cell adenocarcinomas from other organs, particularly the kidney.