Clear cell carcinoma
Clear cell carcinoma, also known as clear cell adenocarcinoma, is a very rare malignant epithelial neoplasm composed of a monomorphous population of cells that have optically clear cytoplasm with standard hematoxylin and eosin stains and lack features of other specific neoplasms. Because of inconsistencies in the methods of reporting salivary gland neoplasms, meaningful incidence rates for this tumor are difficult to derive from the literature. Most cases involve the minor salivary glands.[1,3,39,40,41] In the AFIP case files, the mean age of patients is approximately 58 years.
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]