Section 7 -

High-Grade Salivary Gland Tumors (Dr. Powers) William C. Faquin, M.D., Ph.D. Celeste N. Powers, M.D., Ph.D.

Clinical History: A 52 year-old man presented with a rapidly enlarging right parotid gland mass. The lesion is painful, and the patient has symptoms of facial nerve involvement. An FNAB was performed. Cytologic Findings: The smears were cellular and showed cohesive clusters of epithelial cells with marked nuclear atypia and moderate amounts of vacuolated cytoplasm. Nuclei were enlarged, pleomorphic, and hyperchromatic. Mitotic activity and necrosis were identified. The background contained blood, tumor diathesis, and occasional scattered single malignant cells. Based upon these findings, a cytologic diagnosis of a "high-grade carcinoma, favor salivary duct carcinoma" was made. The lesion was subsequently surgically excised by total parotidectomy and facial nerve sacrifice, revealing a neoplasm with histomorphologic features of salivary duct carcinoma. Section 7 - Figure 1 Section 7 - Figure 2 Discussion: Salivary Duct Carcinoma Salivary duct carcinoma is an uncommon, clinically aggressive malignancy that most commonly occurs in the parotid gland of older to elderly men. It resembles high-grade comedo-type ductal carcinoma of the breast. The cytologic features are those of a high-grade carcinoma. Cells are polygonal with moderate to abundant vacuolated cytoplasm, enlarged hyperchromatic nuclei with prominent nucleoli, and background necrosis. The cells are present in cohesive groups that may form sheets, papillae, and cribriform clusters. Section 7 - Figure 3 Salivary duct carcinoma Cytologic features of salivary duct carcinoma: Overtly malignant cytology Polygonal cells with abundant vacuolated cytoplasm Large hyperchromatic, pleomorphic nuclei Prominent nucleoli Sheets, clusters, papillae, and cribriform groupings Background necrosis Histologic Features of Salivary Duct Carcinoma: This high-grade adenocarcinoma resembles ductal carcinoma of the breast. The most common patterns are comedonecrotic, papillary and cribriform, and both infiltrative and intraductal components are usually seen. Tumor cells are polygonal to cuboidal with moderate amounts of pale cytoplasm, and usually with significant nuclear atypia in the form of pleomorphism and large nucleoli. The desmoplastic stromal reaction is characteristic of this tumor. Section 7 - Figure 4 Salivary duct carcinoma showing a typical comedonecrotic pattern. Differential Diagnosis: The differential diagnosis of salivary duct carcinoma includes other high-grade malignancies of the salivary gland and metastases to salivary glands. In some cases, it may be extremely difficult to distinguish salivary duct carcinoma from high-grade mucoepidermoid carcinoma and carcinoma ex pleomorphic adenoma but clinical management tends to be similar for all of these cases. Distinction from distant metastasis is also difficult and depends on appropriate clinical information. Differential diagnosis of high-grade carcinomas Salivary duct carcinoma High-grade mucoepidermoid carcinoma Carcinoma-ex-pleomorphic adenoma (malignant mixed tumor) Metastatic carcinoma Malignant mixed tumor: Malignant mixed tumor is a rare neoplasm. There are 3 types of malignant mixed tumor: metastasizing mixed tumor, carcinosarcoma, and carcinoma arising in a mixed tumor (carcinoma ex pleomorphic adenoma), the latter being the most common. When pleomorphic adenomas develop a malignant component, it is most commonly in the form of salivary duct carcinoma, although a variety of different salivary gland malignancies can arise, usually they are high-grade! Cytologic features of malignant mixed tumor: Carcinoma ex pleomorphic adenoma High-grade carcinoma (usually salivary duct carcinoma) juxtaposed with typical pleomorphic adenoma Metastasizing mixed tumor Indistinguishable from pleomorphic adenoma Carcinosarcoma Distinct, malignant epithelial and mesenchymal elements Section 7 - Figure 5 Carcinoma-ex-pleomorphic adenoma