Salivary gland cancers are rare. Around 8 out of 10 salivary gland tumors (80%) are in the parotid. Just fewer than 2 out of 10 salivary gland cancers develop in the other two salivary glands - the submandibular or sublingual glands. Fewer than 1 in 10 cancers start in the minor salivary glands. There are many different types of salivary gland cancers. The most common is mucoepidermoid carcinoma (MEC). Just over 3 out of 10 (25-35%) salivary gland cancers (SGT, SGC) are of this type. The others include adenoid cystic carcinoma (ACC), acinic cell carcinoma, carcinoma ex-pleomorphic adenoma (Ca-PA), polymorphous low grade adenocarcinoma (PLGA) and some newly discovered salivary gland tumors. Because of the infrequency of salivary gland tumors and their complex histopathological diagnosis, it is difficult to exactly predict their clinical course by means of its recurrence, malignant progression or metastasis. Salivary gland tumors always pose problems in diagnosis. This review provides an insight into the recent concepts and immunohistochemical markers to diagnose the malignant salivary gland tumors (SGT), thus guiding the Ear, Nose and Throat specialists, Oral and Maxillofacial Surgeons, General Pathologists and other medical and dental specialists thereby enabling them to make correct diagnosis and provide the appropriate treatment.

Plasma cells are terminally differentiated B lymphocytes which are typically found in the red pulp of the spleen, medulla of the lymph nodes, tonsils, lamina propria of the entire gastrointestinal tract, mucosa of the nose and upper airway, and sites of inflammation. They are characterised by basophilic cytoplasm with an eccentrically placed nucleus. They range in size from 14 to 20 µm. A plasma cell's main function is to produce immunoglobulins or antibodies. Plasma cell granuloma is a plasma cell lesion which merits discussion because it is typically found in the oral cavity. This lesion is not a neoplastic process, nor is it associated with a monoclonal expansion of a single plasma cell; instead, this is a reactive, inflammatory lesion which usually involves the gingival tissue.

Oral Submucous Fibrosis (OSF) is a chronic disorder characterized by fibrosis of the mucosa lining the upper digestive tract involving the oral cavity, oro- and hypopharynx and the upper third of the oesophagus. The alkaloids from areca nut are the most important chemical constituents biologically, in producing this lesion. These chemicals appear to interfere with the molecular processes of deposition and/or degradation of extracellular matrix molecules such as collagen. Increased collagen synthesis or reduced collagen degradation have been considered as a possible mechanism in the development of the disease. Increased and continuous deposition of extracellular matrix may also take place as a result of disruption of the equilibrium between matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMP). Arecoline a product of areca nut was found to elevate Cystatin C mRNA (CST3) and protein expression in a dose-dependent manner. Cystatin C expression was significantly higher in OSF specimens and expressed mainly by fibroblasts, endothelial cells, and inflammatory cells. Cross-links between the molecules are essential for the tensile strength of collagen fibres. These areas are resistant to attack by collagenases but can be attacked by a number of other serine and cysteine proteinases. CST3 encoding a cysteine proteinase inhibitor might contribute to the stabilization of collagen fibrils in OSMF. Treatment directed against Cystatin C may serve as a novel treatment for submucous fibrosis and also in preventing its transformation into malignancy.

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