Sialoblastoma: A Case Report and Review of the Literature on Congenital Epithelial Tumors of Salivary Gland Origin

The histologic, immunohistochemical, and ultrastructural features of a congenital epithelial tumor of the parotid were studied. The tumor was characterized by solid nests of epithelial cells intermingled with proliferating ductal structures lined by a double layer of cells. Immunoperoxidase staining for cytokeratin, vimentin, actin, and S-100 protein showed the presence of cytokeratin in the ductal cells as well as the presence of vimentin, actin, and S-100 protein in the outermost layer of the ducts. The solid nests were focally reactive to S-100 and vimentin. Ultrastructural examination revealed myoepithelial cells with replication of basement membrane material. The tumor recurred 17 months after excision without lymph node involvement or metastasis. The term “sialoblastoma” is favored. Review of the literature on congenital, epithelial salivary gland tumors showed that a few cases recurred locally and only one case had regional lymph node involvement. No distant metastasis has been reported.