Dent 356-11 Diseases of Salivary Glands II

1. Dent 356-11Diseases of Salivary Glands II Sialadenosis HIV-Associated Salivary Gland Disease Salivary Gland Tumors Age Changes Dr. Huda Hammad

2. Sialadenosis (Sialosis) Non-inflammatory, non-neoplastic, recurrent bilateral swelling of salivary glands. Parotid glands most commonly. Probably due to abnormalities of neurosecretory control.

3. Sialadenosis (Sialosis) Has been reported with: Hormonal disturbances. Malnutrition. Liver cirrhosis. Chronic alcoholism. Various drugs.

4. Sialadenosis (Sialosis) Histopathology: Hypertrophy of serous acinar cells to about twice their normal size. Cytoplasm is densely packed with secretory granules.

5. HIV-Associated Salivary Gland Disease May be a feature in a small number of adults with HIV infection. Prevalence may be higher in children. Xerostomia and/or swelling of major glands, especially parotid. Xerostomia may be caused by a Sjögren syndrome-like process associated with myoepithelial sialadenitis. However, there is no autoantibody profile as seen with Sjögren syndrome.

6. HIV-Associated Salivary Gland Disease HIV-related parotid enlargement may be due to: Persistent glandular lymphadenopathy. Multiple lymphoepithelial cysts.

7. Salivary Gland Tumors Uncommon. Geographical variation. Tumors of major glands more common than minor (15-20%).

8. Salivary Gland Tumors In major glands , parotid tumors comprise ~90%. 55% of minor gland tumors affect palate, 20% upper lip. Tumors of sublingual gland and lower lip glands are rare.

9. Salivary Gland Tumors Proportion of malignant tumors in minor glands is higher than benign. Opposite is true for major glands. Rare salivary gland tumors occur as central intraosseous lesions of the jaws, either from entrapped salivary tissue or from lining of odontogenic cysts.

10. Salivary Gland Tumors: Classification

11. Pleomorphic Adenoma (Mixed Tumor) Commonest SG tumor, 60-65% of parotid tumors, 45% of minor gland tumors. 7% originate in minor glands, especially palatal. Predilection to old age and females. Usually solitary, recurrences may be multifocal.

12. Pleomorphic Adenoma: Clinical Features Slowly growing, painless, rubbery swelling with intact overlying skin or mucosa. Patient may be aware of lesion for several years.

13. Pleomorphic Adenoma: Histopathologic Features Composed of cells of epithelial and myoepithelial origin. Great variety with complex intermingling of components & mesenchyme-like areas, hence the 2 names. Although benign, CT capsule is not always complete. Clearly demarcated , but apparently isolated nodules may be seen within or even outside the capsule giving the impression of invasive growth.

14. Pleomorphic Adenoma: Histopathologic Features Serial sections show that these represent outgrowths of the main mass. These islands explain the need for excision with a margin to avoid recurrence. Considerable variation in arrangement of epithelial and stromal components between different tumors and within different areas of same tumor. Epithelial component may be arranged in duct-like structures, sheets, clumps, and interlacing strands.

15. Pleomorphic Adenoma: Histopathologic Features Epithelial-duct cells and myoepithelial-type cells. Polygonal, spindle, stellate, or plasmacytoid cells thought to be derived from myoepithelium. Areas of squamous metaplasia and keratin pearl formation may be present. Intercellular material varies in quantity and quality: fibrous, hyalinized, myxoid, chondroid, or myxochondroid.

16. Pleomorphic Adenoma: Histopathologic Features Tumors rich in mucoid material (glycosaminoglycans) tend to rupture during surgical removal allowing spillage and implantation of tumor and multiple recurrences. Malignant transformation can occur, usually in tumors present for many years.

17. Warthin Tumor (Papillary Cystadenoma Lymphomatosum) Occurs almost exclusively in the parotid. Slow-growing. May be multifocal. May bilateral (5-10%). Predilection for old age. Most likely arises from residual salivary duct epithelium entrapped within lymph nodes during development.

18. Warthin Tumor: Gross Appearance Multiple, irregular cystic spaces ( C ) of variable size containing mucoid material. The lining of the cysts has small projections that represent the papillary structures.

19. Warthin Tumor: Histopathologic Features Multiple, irregular cystic spaces containing mucoid material separated by papillary projections of tumor tissue. Tumor consists of: Epithelial component: double-layered epithelium lining cystic spaces in papillary arrangement. Lymphoid component within stroma, may contain germinal centers. Epithelial cells have granular cytoplasm rich in abnormal mitochondria, resembling oncocytes.

20. Basal Cell Adenoma: Clinical Features 1-2% of all SG tumors. 70% in parotid, 20% in upper lip. Peak incidence in 7th decade.

21. Basal Cell Adenoma: Histopathologic Features Consists of cytologically uniform basaloid cells arranged in a variety of patterns. Well-encapsulated.

22. Oncocytoma Rare tumor. Usually arises in parotid. >60 years of age. Thin capsule. Consists of oncocytes; large cells with granular eosinophilc cytoplasm rich in mitochondria. D/D oncocytic hyperplasia.

23. Canalicular Adenoma > 50 years of age. Almost all cases in upper lip. Consists of anastomosing strands of basaloid epithelial cells arranged in canalicular structures. May be partly or grossly cystic due to degeneration of loose vascular stroma.

24. Canalicular Adenoma In some cases, multiple microscpic foci multicentric) seen in surrounding minor salivary gland tissue. Do not appear to be of clinical significance and do not represent invasive growth.

25. Ductal Papillomas Rare tumors. Papillary structure projecting into the ductal system. Several subtypes.

26. Adenocarcinomas Relatively uncommon. 1% or less of all body malignancies, ~5% of head and neck malignancies. Most frequently in major glands, especially parotid. However, ratio of malignant to benign in minor glands is higher than in major glands.

27. Mucoepidermoid Carcinoma ~10% of all salivary gland tumors. Most arise in parotid. In minor glands, the palate is the most common site. Highest incidence in 4th & 5th decades.

28. Mucoepidermoid Carcinoma: Clinical Features Often presents clinically in a similar manner to pleomorphic adenoma. Grossly cystic tumors may be fluctuant. More aggressive tumors may cause pain and ulceration.

29. Mucoepidermoid Carcinoma: Histopathologic Features Characterized by presence of 3 cell types: squamous (epidermoid), mucous, and intermediate. Relative proportions and arrangements of cell types are used to distinguish between: High grade MEC. Low grade MEC.

30. Mucoepidermoid Carcinoma: Histopathologic Features Low grade MEC: Well-differentiated. Mucous and epidermoid cells predominate. No cellular pleomorphism. Often cystic, cysts being lined by mucus-secreting cells. Epidermoid cells present in strands or clumps, may show keratinization. 6. Rupture of mucin-containing cysts may lead to inflammation. 7. Advance on a broad, pushing front.

31. Mucoepidermoid Carcinoma: Histopathologic Features High grade MEC: Poorly differentiated. Epidermoid and intermediate cells predominate. Nuclear & cellular pleomorphism and atypia. Cystic spaces not prominent. 5. Differentiation from SCC may be difficult. 6. Ill-defined and highly infiltrative.

32. Mucoepidermoid Carcinoma: Prognosis Low grade tumors rarely metastasize. However, behavior cannot be accurately predicted from histopathology. Overall 5-year survival rate ~70%. Low grade tumors 5-year survival rate ~95%, local recurrence <10%. High grade tumors 5-year survival rate ~30-40%, local recurrence 80%.

33. Acinic Cell Carcinoma Uncommon. Accounts for 2-3% of parotid tumors. Regarded as a low grade malignancy. 80-100% 5-year survival rates reported for well-differentiated tumors, 65% for poorly differentiated ones.

34. Acinic Cell Carcinoma: Histopathologic Features Spectrum of histopathological appearances. The most common variants consist of sheets or acinar groupings of large, polyhedral cells with basophilic, granular cytoplasm, similar to serous acinar cells.

35. Adenoid Cystic Carcinoma Middle-aged & elderly. Up to 30% of minor SG tumors, but only ~6% of parotid tumors.

36. Adenoid Cystic Carcinoma: Clinical Features May present as slowly enlarging tumors like pleomorphic adenoma, but pain and ulceration are much more common. Parotid tumors may present with facial palsy. Neurological manifestations reflect predilection to infiltrate and spread along nerves.

37. Adenoid Cystic Carcinoma: Histopathologic Features Wide spectrum of appearances. Most commonly, epithelium is arranged as ovoid & irregularly shaped islands or anastomosing cords and strands in scanty CT stroma. Numerous microscopic cyst-like spaces within epithelial islands produce a cribriform or “Swiss cheese” pattern. Epithelium consists of small, uniform, basophilic cells. Rare mitoses.

38. Adenoid Cystic Carcinoma: Histopathologic Features Perineural invasion. Less commonly epithelium is arranged in a tubular or solid pattern. Prominent infiltration and invasion of adjacent tissues, and spread around and along nerves. In the maxilla, tumor may infiltrate along marrow spaces with no evidence of bone destruction.

39. Adenoid Cystic Carcinoma: Prognosis Radiotherapy may be used for inoperable cases, but does not result in permanent cure. Runs a prolonged clinical course and metastases are late, usually to lungs. Long term prognosis is poor. 5-year survival rates for parotid tumors are 75%, 10-year rates are 40%, 20-year are <15%. Cribriform and tubular types have better prognosis than solid type. It is even less favorable in minor glands.

40. Carcinoma Arising in Pleomorphic Adenoma Also known as carcinoma ex pleomorphic adenoma. ~3% of SG tumors. Almost all arise in parotid or submandibular tumors that have been present for many years. Histological diagnosis requires evidence of pre-existing pleomorphic adenoma.

41. Carcinoma Arising in Pleomorphic Adenoma Malignant component may be an adenocarcinoma or undifferentiated carcinoma, or other types of SG malignancy. When the malignant part is confined within pre-existing tumor, prognosis is excellent. When there is infiltration of surrounding tissues there is poor prognosis. Some mixed tumors arise as malignant de novo*.

42. Polymorphous Low Grade Adenocarcinoma Occurs almost exclusively in minor glands. Most arise in the palate. Good prognosis. Unpredictable potential to metastasize in ~15% of cases.

43. Polymorphous Low Grade Adenocarcinoma: Histopathologic Features Shows a variety of growth patterns within the same lesion, including solid, tubular, papillary, & cribriform. Cytologically uniform and bland with infrequent mitoses and lack of atypia. D/D adenoid cystic carcinoma, both show perineural invasion. Histologic patterns: linear single cells (Indian file) (A); tubular (B); solid (C); fascicular (streaming) (D). Additional histologic patterns: myxoid (A); cribriform (pseudoadenoid) (B); jigsaw (C); cystic (D).

44. Other Salivary Carcinomas Epithelial myoepithelial carcinoma Basal cell adenocarcinoma Adenocarcinoma; not otherwise specified (NOS)

45. Age Changes in Salivary Glands Reduction in weight of parotid and submandibular glands related to atrophy of secretory tissue & replacement by fibrofatty tissue. Similar changes in labial minor glands. Oncocytic change in ductal epithelium. Reduction in flow rate in submandibular gland.