Clear cell carcinoma parotic in the head and neck area is a rare case. Clear cell carcinoma (CCC) can be found in almost all benign or malignant epithelial, mesenchymal, melanocytic or hematopoietic tumors. CCC occurs due to various factors including artifactual changes, impaired cell preservation and hydropic degeneration of organelles, or due to accumulation of glycogen, mucopolysaccharides, lipids, mucins, or phagocytosed foreign bodies in tumor cells. Clear cell changes in the tumor become more extensive as the tumor progresses or arise secondarily. All these factors make the diagnosis of clear cell difficult. Salivary gland tumors account for less than 7% of neoplasms involving the head and neck region.
Intraosseous salivary gland tumors may arise from ectopic salivary glands, and may arise from neoplastic transformation of mucous cells found in the lining of dentigerous cysts, from embryonic submandibular glands found within the mandible, from bony entrapment of retromolar pad mucous cells during embryogenesis or theoretically, may also arise from salivary glands present within lingual cortical defects of the mandible. The most commonly reported intraosseous salivary gland tumor is mucoepidermoid carcinoma, followed by adenoid cystic carcinoma. Although Primary central CCC originating from the salivary glands is very rare, CCC still needs to be considered as a differential diagnosis of central clear cell tumor .
Hyalinizing clear cell carcinoma (HCCC) was first discovered by Milchgrub et al. on year 1994 as carcinoma gland saliva minor rare Which consists of clear cells that form cords and nests within a hyalinized stroma. HCCC is now classified as ‘‘ clear cell adenocarcinoma’’ in the AFIP fascicle and ‘‘ clear cell carcinoma, not otherwise specified (NOS)’’ by the World Health Organization (WHO). 2 Clear cells are seen in a variety of benign and malignant salivary gland tumors, including benign mixed tumors, myoepithelioma/myoepithelial carcinoma, oncocytoma/oncocytic carcinoma, mucoepidermoid carcinoma, acinic cell carcinoma, polymorphic low-grade adenocarcinoma, and adenoid cystic carcinoma. In most cases, clear cells constitute only a small portion of the cellular content of these neoplasms and the diagnosis is based on identification of classic histomorphologic features and unique growth patterns. Differentiating primary salivary gland tumors from metastatic tumors with clear cell features is critical for diagnostic considerations and decision making.