Sclerosing odontogenic carcinoma: A previously unreported variant of a locally aggressive odontogenic neoplasm without apparent metastatic potential

We describe 3 cases of apparent odontogenic carcinomas that share histologic features not previously reported in the literature. The tumors involved one 72-year-old man and 2 women, 46-year old and 73-year old, respectively. Two cases occurred in the mandile and 1 in the maxilla. The tumor presented as expansile radiolucencies. Histopathologically, they were characterized by small nests and thin cords of small cuboidal or polygonal epithelial cells, featuring, only focally, cytoplasmic clearing. Pleomorphism was not remarkable and mitoses were extremely rare. The most striking feature of malignancy was skeletal muscle and perineural infiltration. Sclerosis of the stroma was remarkable. Immunohistochemically, all tumors stained for cytokeratins (CK) 5/6, CK19, and ϵ-cadherin, the latter exhibiting a fragmented cytoplasmic membranous staining. Positive nuclear staining was obtained with p63. Focal staining for CK7 was seen in 1 case. All tumors were negative for CK20, carcinoembryonic antigen, and CAM5.2. The patients were surgically treated and one of them received adjuvant radiation. Microscopic tumor nests and cords were found far beyond of what surgically seemed to be tumor-free margins. All patients are free of disease 5, 12, and 4 years after treatment, respectively. We propose the name sclerosing odontogenic carcinoma. As current classifications of odontogenic tumors do not include such examples, it is important that pathologists become aware of this entity. Finally, this report supports recent literature on positive nuclear p63 in odontogenic cysts and tumors.