Histopathological Analysis of Salivary Gland Lesions and Role of Immunohistochemistry in Differential Diagnosis

BACKGROUND: Tumors of salivary gland have diverse histological forms and unpredictable clinical behavior. The diverse site of origin and complexity of classification further compound the difficulties in diagnosis. The main application of immunohistochemistry in salivary gland tumors is to demonstrate the existence of myoepithelial/basal cells or luminal cells. OBJECTIVES: 1. To determine the incidence, age, sex, site distribution of lesions in various salivary glands and to study the histomorphological appearance of these lesions. 2. To study the expression of various Immunohistochemical markers in salivary gland tumors. METHODS: Surgically resected specimens received at Department of pathology, Thanjavur Medical College were subjected to histopathological examination. Specimen were fixed in 10% formalin, processed and embedded in paraffin blocks. Serially cut to get sections of 3-5microns thickness, stained with Hemotoxylin and Eosin, Histochemistry and Immunohistochemistry were done wherever necessary. RESULTS: The total number of specimens was 92, of which 41were neoplastic (benign44.56% and malignant 25%) 28 were nonneoplastic. Pleomorphic adenoma was the commonest benign tumor accounting for73.17% of benign tumors. Mucoepidermoid carcinoma was the most common malignant tumor accounting for 52.18% of malignant tumors. Parotid is the common salivary gland involved followed by minor salivary and submandibular gland.salivary gland tumors shows slight female preponderance with male female ratio of 1:1.7. Expression of p63 in pleomorphic adenoma has confirmed the role of myoepithelial cells in the histiogenesis of this tumor. Lack or minimal expression of p63 in Mucoepidermoid indicates minimal myoepithelial cell differentiation in these tumors. CONCLUSION: Histopathology is still the goldern standard for diagnosis of salivary gland tumor. IHC do not directly indicate a def inite diagnosis. It can enhance the accuracy and be a helpful tool when the diagnosis cannot be assessed by histological examination such as cell of origin, cell proliferation and tumor protein expression.