The minor salivary glands are located along the mucosa of the aerodigestive tract, including the oral cavity, nasal cavity, and pharynx, and tumors of the minor salivary glands occurring in various sites are included in the discussion of Variants 1, 2, and 3 above. Tumors of the major salivary glands are considered rare and account for 3% to 5% of all head and neck neoplasms and only 0.5% of all malignancies [106,107]. The most common site is the parotid gland, with about 70% arising from this site [108], followed by the submandibular gland, and lastly the sublingual gland. In general, the risk of malignancy is inversely proportional to the size of the gland. Therefore, the risk of cancer is greater in a sublingual gland lesion as opposed to a lesion in the parotid gland. The majority, approximately 70% to 80%, of these tumors are benign, with the most common benign tumor being pleomorphic adenoma (60%-70%) and Warthin tumor (5%-12%) [107]. A smaller percentage are malignant tumors, of which mucoepidermoid carcinoma, adenoid cystic carcinoma, lymphoma, and acinic cell carcinoma are the most common subtypes [107,109]. Furthermore, intraglandular lymphatic tissue predisposes the parotid glands to metastatic disease from locoregional cancers of the head and neck, as well as from distant tumors including the thyroid, breast, and lung [110]. Patients typically present with a palpable abnormality or pain. When there is perineural spread of disease, the patient may experience weakness of the facial muscles. Surgery is considered the primary treatment in the majority of salivary gland tumors and imaging is obtained in large part to determine feasibility of resection [108]. Imaging plays a crucial role in the characterization of these lesions and is aimed at determining anatomic location, relation to surrounding structures, size, multiplicity, presence of perineural spread, and internal features.
Staging and Post Therapy Assessment of Head and Neck Cancer. The minor salivary glands are located along the mucosa of the aerodigestive tract, including the oral cavity, nasal cavity, and pharynx, and tumors of the minor salivary glands occurring in various sites are included in the discussion of Variants 1, 2, and 3 above. Tumors of the major salivary glands are considered rare and account for 3% to 5% of all head and neck neoplasms and only 0.5% of all malignancies [106,107]. The most common site is the parotid gland, with about 70% arising from this site [108], followed by the submandibular gland, and lastly the sublingual gland. In general, the risk of malignancy is inversely proportional to the size of the gland. Therefore, the risk of cancer is greater in a sublingual gland lesion as opposed to a lesion in the parotid gland. The majority, approximately 70% to 80%, of these tumors are benign, with the most common benign tumor being pleomorphic adenoma (60%-70%) and Warthin tumor (5%-12%) [107]. A smaller percentage are malignant tumors, of which mucoepidermoid carcinoma, adenoid cystic carcinoma, lymphoma, and acinic cell carcinoma are the most common subtypes [107,109]. Furthermore, intraglandular lymphatic tissue predisposes the parotid glands to metastatic disease from locoregional cancers of the head and neck, as well as from distant tumors including the thyroid, breast, and lung [110]. Patients typically present with a palpable abnormality or pain. When there is perineural spread of disease, the patient may experience weakness of the facial muscles. Surgery is considered the primary treatment in the majority of salivary gland tumors and imaging is obtained in large part to determine feasibility of resection [108]. Imaging plays a crucial role in the characterization of these lesions and is aimed at determining anatomic location, relation to surrounding structures, size, multiplicity, presence of perineural spread, and internal features.