An Integrated Cytologic and Histologic Approach to the Diagnosis of Salivary Gland Tumors
Section 7 -
High-Grade Salivary Gland Tumors (Dr. Powers)
William C. Faquin, M.D., Ph.D.
Celeste N. Powers, M.D., Ph.D.
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.
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.
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
Cytologic features of salivary duct carcinoma:
- Overtly malignant
- Polygonal cells with abundant
- Large hyperchromatic,
- Prominent nucleoli
- Sheets, clusters, papillae, and
- 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.
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
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
- Distinct, malignant epithelial
and mesenchymal elements