In most patients, swelling is the only symptom. Clear cell adenocarcinoma is a low-grade neoplasm. As of 1996, the AFIP reported that no patient is known to have died as a result of this tumor.
Cystadenocarcinoma, also known as malignant papillary cystadenoma, mucus-producing adenopapillary, or nonepidermoid, carcinoma; low-grade papillary adenocarcinoma of the palate; and papillary adenocarcinoma, is a rare malignant epithelial tumor characterized histologically by prominent cystic and, frequently, papillary growth but lacking features that characterize cystic variants of several more common salivary gland neoplasms. Cystadenocarcinoma is the malignant counterpart of cystadenoma.
In a review that included 57 patients, the AFIP found that men and women are affected equally; the average patient age was approximately 59 years; and approximately 65% of the tumors occurred in the major salivary glands, and primarily in the parotid. Most patients present with a slowly growing asymptomatic mass. Clinically, this neoplasm is rarely associated with pain or facial paralysis. Cystadenocarcinoma is considered to be a low-grade neoplasm.
Sebaceous adenocarcinoma is a rare malignant epithelial tumor composed of islands and sheets of cells that have morphologically atypical nuclei, an infiltrative growth pattern, and focal sebaceous differentiation. This is a very rare tumor, as few cases have been reported in the literature. Almost all cases occur in the parotid gland. The average age of patients is reported to be 69 years.
An equal number of patients present with a painless, slow-growing, asymptomatic swelling or pain. A few experience facial paralysis. Most sebaceous adenocarcinomas are probably intermediate-grade malignancies. Tumor recurs in about 33% of cases.[43,44]
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.