Abstract
A rare case of salivary duct carcinoma with sebaceous cell differentiation arising in the parotid gland of a 78-year-old man was studied. The tumor consisted of large polyhedral cells with pale eosinophilic clear cytoplasms in which many vesicles were included. These tumor cells were arranged in a sheet-like appearance forming cellular nests separated by prominent fibrous stroma. Comedo-type central necrosis and cyst- or duct-like spaces were observed in the nests. The latter histogical feature resulted in the cribriform appearance. Papillary proliferation was co-existent in a small part of the tumor tissue. Considerable number of oil red O- and Sudan III-positive sebaceous cells were observed in the tumor tissue. Electron microscopic observations revealed a number of intracytoplasmic vesicles which were thought to be fat droplets. Based upon these histological features, the present case was diagnosed as salivary duct carcinoma with sebaceous cell differentiation. Immunohistochemical staining for the epithelial membrane antigen and the actin suggested that the salivary duct carcinoma originated in the epithelial cell of the intercalated. However, this issue is still open to question.
