Sebaceous lymphadenocarcinoma is an extremely rare malignant tumor that represents carcinomatous transformation of sebaceous lymphadenoma. The carcinoma element may be sebaceous adenocarcinoma or some other specific or nonspecific form of salivary gland cancer. Only three cases have been reported in the literature.[43,45] The three cases occurred in or around the parotid gland. All patients were in their seventh decade of life. Two of the three patients were asymptomatic. One had tenderness on palpation. Case reports suggest that this is a low-grade malignancy with a good prognosis.[44,45]
Oncocytic carcinoma, also known as oncocytic adenocarcinoma, is a rare, predominantly oncocytic neoplasm whose malignant nature is reflected both by its abnormal morphologic features and infiltrative growth. Oncocytic carcinoma represents less than 1% of almost 3,100 salivary gland tumors accessioned to the AFIP files during a 10-year period. Most cases occur in the parotid gland. The average age of patients in the AFIP series was 63 years.
Approximately 33% of the patients usually develop parotid masses that cause pain or paralysis. Oncocytic carcinoma is a high-grade carcinoma. Tumors smaller than 2 cm have a better prognosis than larger tumors.
Salivary duct carcinoma
Salivary duct carcinoma, also known as salivary duct adenocarcinoma, is a rare, typically high-grade malignant epithelial neoplasm composed of structures that resemble expanded salivary gland ducts. A low-grade variant exists. Incidence rates vary depending upon the study cited. In the AFIP files, salivary duct carcinomas represent only 0.2% of all epithelial salivary gland neoplasms. More than 85% of cases involve the parotid gland and approximately 75% of patients are men. The peak incidence is reported to be in the seventh and eighth decades of life.
Clinically, parotid swelling is the most common sign. Facial nerve dysfunction or paralysis occur in more than 25% of patients and may be the initial manifestation. The high-grade variant of this neoplasm is one of the most aggressive types of salivary gland carcinoma and is typified by local invasion, lymphatic and hematogenous spread, and poor prognosis.[3,7] In a retrospective review of 104 cases, 33% of patients developed local recurrence, and 46% of patients developed distant metastasis.