W6 Slides

Diseases of the salivary glands¹

Histopathology Lab²³

Mucocele (Slide ID 753)⁴⁵

• Mucocele is defined as a mucus-filled cyst that may appear in the oral cavity, gall bladder, paranasal sinuses, or lacrimal sac.
• It is a benign, mucus-containing cystic lesion of the minor salivary gland.
• Mucocele forms because of salivary gland mucous extravasation or retention and is usually related to trauma in the area of the lower lips.
• It occurs either due to rupture of salivary gland duct or by blockade of salivary gland duct.
• The more common type is a mucus extravasation cyst; the other is a mucus retention cyst.
• Salivary duct cyst, however, is a type of mucous retention cyst which is almost never located on the lower lip.

Necrotizing Sialometaplasia (Slide ID 756)^{67891011121314}

• Necrotizing sialometaplasia is a benign, self-limiting inflammatory reaction of salivary gland tissue which may mimic squamous cell carcinoma or mucoepidermoid carcinoma, both clinically and histologically, that creates diagnostic dilemma leading to unwarranted aggressive surgery.

• Necrotizing sialometaplasia (NS) was first reported by Abrams et al in the year 1973.

• This condition has been described as non-neoplastic inflammatory salivary gland disease and benign, self-limiting, reactive inflammatory disorder of salivary tissue.

• NS can resemble a malignancy and its misdiagnosis has resulted in unnecessary radical surgery.

https://onlinelibrary.wiley.com/doi/full/10.1002/ccr3.3931

Pleomorphic Adenoma (Slide ID 764)^{15161718192021}

• Also called benign mixed tumor.
• Most common tumor of salivary glands.
• It is a painless, slow growing tumor, composed of biphasic population of epithelial and mesenchymal cells.
• Typically has 3 components:
  • Epithelial (ductal) component forming the inner layer of cysts and tubules
  • Myoepithelial cells as the outer layer of cysts and tubules and scattered within the myxoid stroma
    • Cytology of myoepithelial cells can be plasmacytoid, spindled, epithelioid, clear or stellate shaped
  • Stromal component is typically myxoid, chondroid or myxochondroid
    • It can also be hyalinized or fibrotic
• Metaplastic changes may be seen, e.g. adipose metaplasia, osseous metaplasia, squamous metaplasia (sometimes with keratinization), sebaceous metaplasia and mucinous metaplasia.

Adenoid Cystic Carcinoma (Slide ID 769)^{22232425262728}

• Deceptively benign histologic appearance and cribriform, solid or tubular pattern similar to cylindroma of skin ([Arch Pathol Lab Med 2011;135:511](Arch Pathol Lab Med 2011;135:511)).
• Most common in submandibular, sublingual or minor salivary glands.
  • Also seen in nose, sinus, upper airway.
• 22% of salivary gland malignancies.

Microscopic description

• Cribriform, solid or tubular pattern similar to cylindroma of skin.
• Small bland myoepithelial cells with scant cytoplasm and dark compact angular nuclei surround pseudoglandular spaces with PAS+ excess basement membrane material and mucin.
• Peripheral perineurial invasion and small true glandular lumina.
• No squamous differentiation, no extensive necrosis.

Clinical features²⁹³⁰

• Occurs in fifth to sixth decades.
• Male predominance.
• Slow growing, indolent but aggressive.
• Recurrences are frequent.
  • Often late and difficult to predict.
• Rarely lymph node metastases.
• 5 year survival is 60%, 10 year is 30%, 15 year is 15%.

Mucoepidermoid Carcinoma (Slide ID 770)^31323334

• 2/3 occur in parotid gland; also in palate.
• Wide age range, mean 49 years, range 15 - 86 years, no gender predominance.
• Low grade: 15% recur, 5 year survival 90 - 98%, usually stage I.
• High grade: 25% recur, 5 year survival 50 - 56%, deaths usually within first 5 years. (Am J Surg Pathol 2001;25:835)

Microscopic description

• Cords, sheets and clusters of mucous, squamous, intermediate and clear cells.
• Low to high grade, although even high grade tumors lack marked nuclear atypia, frequent mitotic figures or extensive necrosis.
• Occasional focal sebaceous cells, goblet type cells, oncocytic change, inflammatory reaction to extravasated mucin or keratin.
• No squamous cell carcinoma in situ.
• Low grade: mucinous and intermediate cells with bland nuclei form glandular spaces.
• High grade: solid and infiltrative growth pattern of atypical epidermoid and intermediate cells with cytoplasmic clearing and small number of mucinous cells; < 20% intracystic component.

Mucoepidermoid Carcinoma^353637383738

• 2/3 occur in parotid gland; also in palate
• Wide age range, mean 49 years, range 15 - 86 years, no gender predominance
• Low grade: 15% recur, 5 year survival 90 - 98%, usually stage I
• High grade: 25% recur, 5 year survival 50 - 56%, deaths usually within first 5 years (Am J Surg Pathol 2001;25:835)

Footnotes

1. Original PDF page 1: W6 Slides, p.1 ↩

2. Original PDF page 2: W6 Slides, p.2 ↩

3. Original PDF page 3: W6 Slides, p.3 ↩

4. Original PDF page 4: W6 Slides, p.4 ↩

5. Original PDF page 5: W6 Slides, p.5 ↩

6. Original PDF page 6: W6 Slides, p.6 ↩

7. Original PDF page 7: W6 Slides, p.7 ↩

8. Original PDF page 8: W6 Slides, p.8 ↩

9. Original PDF page 9: W6 Slides, p.9 ↩

10. Original PDF page 10: W6 Slides, p.10 ↩

11. Original PDF page 11: W6 Slides, p.11 ↩

12. Original PDF page 12: W6 Slides, p.12 ↩

13. Original PDF page 13: W6 Slides, p.13 ↩

14. Original PDF page 14: W6 Slides, p.14 ↩

15. Original PDF page 15: W6 Slides, p.15 ↩

16. Original PDF page 16: W6 Slides, p.16 ↩

17. Original PDF page 17: W6 Slides, p.17 ↩

18. Original PDF page 18: W6 Slides, p.18 ↩

19. Original PDF page 19: W6 Slides, p.19 ↩

20. Original PDF page 20: W6 Slides, p.20 ↩

21. Original PDF page 21: W6 Slides, p.21 ↩

22. Original PDF page 22: W6 Slides, p.22 ↩

23. Original PDF page 23: W6 Slides, p.23 ↩

24. Original PDF page 24: W6 Slides, p.24 ↩

25. Original PDF page 25: W6 Slides, p.25 ↩

26. Original PDF page 26: W6 Slides, p.26 ↩

27. Original PDF page 27: W6 Slides, p.27 ↩

28. Original PDF page 28: W6 Slides, p.28 ↩

29. Original PDF page 29: W6 Slides, p.29 ↩

30. Original PDF page 30: W6 Slides, p.30 ↩

31. Original PDF page 31: W6 Slides, p.31 ↩

32. Original PDF page 32: W6 Slides, p.32 ↩

33. Original PDF page 33: W6 Slides, p.33 ↩

34. Original PDF page 34: W6 Slides, p.34 ↩

35. Original PDF page 35: W6 Slides, p.35 ↩

36. Original PDF page 36: W6 Slides, p.36 ↩

37. Original PDF page 37: W6 Slides, p.37 ↩ ↩²

38. Original PDF page 38: W6 Slides, p.38 ↩ ↩²