Salivary glands (1).pptx from wachemo university lecture best notes.Please every one read it!
- 1. Salivary glands • There are two main groups of salivary glands —major and minor. • The major salivary glands are the three paired glands: parotid, submandibular and sublingual. • The minor salivary glands are numerous and are widely distributed in the mucosa of oral cavity.
- 6. • Inflammatory or neoplastic disease may develop within any of the salivary glands Inflammation (Sialadenitis) • Inflammation of the salivary glands may be of traumatic, viral, bacterial, or autoimmune origin.
- 7. Mucocele • The most common type of inflammatory lesion of the salivary glands • It results from blockage or rupture of a salivary gland duct, with consequent leakage of saliva into the surrounding tissues. • Mucoceles are most often found in the lower lip, as a consequence of trauma. • They occur at all ages but are most common in toddlers, young adults, and the elderly, who are more prone to falling
- 8. • Clinically, they present as fluctuant swellings of the lower lip that have a blue translucent hue • Histologically, mucoceles are pseudocysts with cyst-like spaces lined by inflammatory granulation tissue or by fibrous connective tissue. • The cystic spaces are filled with mucin and inflammatory cells, particularly macrophages
- 12. Viral sialadenitis • The most common form of viral sialadenitis particularly of the parotid glands, is mumps occurring in children of school-age which usually produce bilateral enlargement of the salivary glands • Mumps virus is a paramyxovirus, an RNA virus which is transmitted by inhalation of respiratory droplets. • Although childhood mumps is self-limited and rarely creates residual problems, mumps in adults may be accompanied by pancreatitis or orchitis; the latter sometimes causes permanent sterility.
- 15. Bacterial sialadenitis • Most occur in major salivary glands, particularly the submandibular glands which may be acute or chronic • Most often occurs secondary to ductal obstruction resulting from stone formation (sialolithiasis) • Decreased secretory function may also predispose to secondary bacterial invasion, as sometimes occurs in patients receiving drugs that suppress salivary secretion for longer duration (e.g. antihistamines, antihypertensives, antidepressants) • Decreased salivary secretions caused by dehydration may lead to the development of bacterial suppurative parotitis in elderly patients with a recent history of major thoracic or abdominal surgery because of retrograde entry of oral cavity bacteria • The most common bacteria causing the infection are Staphylococcus aureus and Streptococcus viridans.
- 16. • Whatever the origin, the obstructive process and bacterial invasion lead to a nonspecific inflammation of the affected glands that may be largely interstitial or, when induced by staphylococcal or other pyogens, may be associated with overt suppurative necrosis and abscess formation. • The inflammatory involvement causes painful enlargement and sometimes a purulent ductal discharge. • Unilateral involvement of a single gland is the rule.
- 19. Chronic sialadenitis • This may result from the following causes: –Recurrent obstruction mainly due to calculi (sialolithiasis) may cause repeated attacks of acute sialadenitis and then chronicity. –Recurrent non-obstructive type -arises from decreased production of saliva with subsequent inflammation. –Chronic inflammatory diseases – Tuberculosis –Autoimmune disease
- 20. - Autoimmune sialadenitis, is almost invariably bilateral. - This is seen in Sjögren syndrome, All of the salivary glands (major and minor), as well as the lacrimal glands, may be affected in this disorder, which results in dry mouth (xerostomia) and dry eyes (keratoconjunctivitis sicca). - The combination of salivary and lacrimal gland inflammatory enlargement, which is usually painless with xerostomia, whatever the cause, is sometimes referred to as Mikulicz syndrome. - The causes include sarcoidosis, leukemia, lymphoma, and idiopathic lymphoepithelial hyperplasia.
- 23. Salivary Gland Tumors • The salivary glands give rise to a variety of benign and malignant tumors. • They represent less than 2% of all tumors in humans. • About 65% to 80% arise within the parotid, 10% in the submandibular gland, and the remainder in the minor salivary glands, including the sublingual glands.
- 24. - In the parotids 15-30% of these tumors are malignant , whereas 40% of submandibular glands, 50% in minor salivary glands & 70 to 90% in sublingual glands are malignant . - The likelihood of a salivary gland tumor being malignant is more or less inversely proportional to the size of the gland.
- 25. • These tumors usually occur in adults, with a slight female predominance, but about 5% occur in children younger than age 16 years. • The benign tumors most often appear in the fifth to seventh decades of life. • The malignant ones tend to appear somewhat later. • Whatever the histologic pattern, neoplasms in the parotid glands produce distinctive swellings ( 4-6cm mobile swelling except in the case of neglected malignant tumors) in front of and below the ear. • Cancers are generally detected more quickly because of their rapid growth • The dominant tumor arising in the parotids is the benign pleomorphic adenoma
- 26. • Rare- Mesenchymal benign and malignant tumors, Lymphomas, melanoma, ,metastases
- 27. Pleomorphic Adenoma (Mixed Tumor of Salivary Glands) • They are benign tumors that show epithelial and mesenchymal differentiation • Because of their remarkable histologic diversity, (pleomorphic or ‘mixed’ appearance) these neoplasms have also been called mixed tumors • This tumor Represents about 60% of tumors in the parotid , are less common in the submandibular glands, and are relatively rare in the minor salivary glands • They are thought to arise from either myoepithelial or ductal reserve cells • Radiation exposure increases the risk • The tumor is common in women and is seen more frequently in 3rd to 5th decades of life.
- 28. Morphology • It is a slow-growing, solitary well-demarcated, apparently encapsulated lesion. • Most often arising in the superficial parotid, it usually causes painless swelling at the angle of the jaw. • Histologically it is characterised by pleomorphic or ‘mixed’ appearance in which epithelial elements are dispersed throughout the matrix along with varying degrees of myxoid, hyaline, chondroid (cartilaginous), and even osseous tissue.
- 35. • These tumors present as painless, slow-growing, mobile, discrete masses within the parotid or submandibular areas or in the buccal cavity • Despite the tumor's encapsulation, histologic examination often reveals multiple sites where the tumor penetrates the capsule. • Adequate margins of resection are thus necessary to prevent recurrences. • The recurrence rate with parotidectomy is about 4% but, with simple enucleation approaches 25%.
- 36. • Carinoma arising in pleomorphic adenoma is referred as carcinoma ex pleomorphic adenoma or a malignant mixed tumor • Malignant transformation increases with duration • The cancer usually takes the form of an adenocarcinoma or undifferentiated carcinoma. • They are among the most aggressive of all salivary gland malignant neoplasms, producing mortality rates of 30% to 50% at 5 years.
- 37. Warthin’s tumor (adenolymphoma, Papillary Cystadenoma Lymphomatosum) • The second most common benign salivary gland neoplasm accounting for 5-10% of salivary gland tumors • It arises almost exclusively in the parotid gland and occurs more commonly in males than in females, usually in the fifth to seventh decades of life. • Smokers have eight times the risk of nonsmokers for developing these tumors
- 38. • It is benign round to oval encapsulated masses, 2 to 5 cm in diameter, usually arising in the superficial parotid gland with narrow cystic or cleftlike spaces filled with mucinous or serous secretions on cut section • Histology: Spaces lined by a double layer of epithelial cells with oncocytic columnar cells in the upper layer and cuboidal to polygonal cells in the lower layer resting on a dense lymphoid stroma sometimes bearing germinal centers • These neoplasms are benign, with recurrence rates of only 2% after resection.
- 42. Malignant tumors include - Mucoepidermoid tumor - Adenoid cystic carcinoma - Acinic cell carcinoma - Malignant mixed tumour (Carcinoma in pleomorphic adenoma)
- 43. Mucoepidermoid carcinoma • Most common form of primary malignant tumor of salivary glands • 15% of all salivary gland tumors • Occur mainly in the parotids(60% to 70%), b/n 30-60yrs but it is also the most common malignant salivary gland tumour affecting children and adolescents. • Usually circumscribed but not encapsulated ,infiltrative • Composed of mixtures of three cells: squamous cells, mucus secreting cells, and intermediate cells • Cords, sheets, or cystic configurations of squamous, mucous, or intermediate cells • Low grade lesions tend to be composed of largely mucus secreting cells • High grade tumors are composed largely of squamous cells with only a scattering of mucus secreting cells • The clinical course and prognosis depend on the grade of the neoplasm.
- 46. Adenoid cystic carcinoma • Uncommon tumor, which in approximately 50% of cases is found in the minor salivary glands • Among the major salivary glands, the parotid and submandibular glands are the most common locations. • They are poorly encapsulated, infiltrative tumors • Composed of small cells, having dark, compact nuclei and scanty cytoplasm • The cells tend to be dispersed in tubular, solid, or cribriform patterns • The spaces between tumor cells are filled with a hyaline material • Most painful (perineural invsasion) salivary gland neoplasm • Has high rate of reccurence and metastasis
- 48. Acinic Cell Carcinoma • It is relatively uncommon, representing only 2% to 3% of salivary gland tumors. • It is composed of cells resembling the normal serous acinar cells of salivary glands • Most arise in the parotids; the remainder arise in the submandibular glands • Has better prognosis the MEC and ACC