Nasal polyps are soft, fleshy masses that can arise from the nasal mucosa. Histologically, there are different types of nasal polyps ranging from inflammatory to neoplastic. The most common type is the oedematous allergic nasal polyp, which is lined by thickened epithelium and contains eosinophils, plasma cells and lymphocytes in the submucosa. Chronic inflammatory polyps can develop from traumatized allergic polyps and contain submucosal fibrosis. Rarely, seromucinous polyps can occur due to glandular hyperplasia. Microscopic examination is important for classification and diagnosis of underlying conditions.

1. Pathology of nasal polyp Dr T Balasubramanian

3. Histopathologically these polyp can be very diverse ranging from simple inflammatory to bening / malignant neoplasm

4. Polyp due to chronic rhinosinusitis can be described as non granulomatous inflammatory tissue projecting from the nasal mucosa

6. Structural components – Surface epithelium, basement membrane and submucosal tissue

7. Non structural components – Resident / Non resident cells of lymphoid / Myeloid origin

9. The rest of the nasal cavity is lined by respiratory type of epithelium (Schneiderian membrane)

10. The lining mucosa of paranasal sinuses is rather thinn when compared to that of nasal cavity

12. It is composed of 4 cell types – ciliated columnar / cuboidal cells, interspaced goblet cells, nonciliated columnar cells with microvilli and basal cells

13. The ratio of columnar : goblet cells is 5:1

14. Columnar epithelium contains tight junctions and rest on the basement membrane

15. Squamous metaplasia is common due to exposure

16. Point to remember Whitish fleshy nasal polyp indicates Squamous Metaplasia due to drying effects caused by Exposure to atmosphere

18. Other constituents include: Heparan sulfate proteoglycan, laminin and Nidogen

19. The basement membrane is thin and delicate in the whole of nasal cavity except for inferior turbinate area.

21. Lines superior turbinate, superior portion of nasal septum, roof of nasal cavity and medial portions of middle turbinate

22. This epithelium is also pseudostratified ciliated columnar containing bipolar olfactory cells, microvillar cells and supporting sustentacular cells

23. ! Note Due to aging / infections olfactory Epithelium could be replaced by Normal nasal mucosa

25. Overlies the cartilagenous / bony framework of nasal cavity

26. Contains loose fibrovascular connective tissue, seromucinous / minor salivary glands, blood vessels, nerves, myeloid and lymphoid cells

27. Blood vessels contains many av anastomosis

28. Blood vessels communicate with venous erectile tissue which are prominent over inferior turbinates

30. Components of lymphoid tissue include single lymphocytes scattered among the epithelial cells and lamina propria and NALT

32. Similar to Payer's patch of intesting

33. Unencapsulated

34. Becomes enlarged during nasal infections

36. B cells

37. Plasma cells

38. Natural Killer cells

40. Samter's triad (Bronchial asthma, aspirin hypersensitivity and nasal polyposis)

41. Eosinophilic chronic rhinosinusitis including AFRS

42. Cystic fibrosis

43. Young's syndrome

44. Churg – Strauss disease

46. Soft in consistency when compared to surrounding nasal mucosa

47. Long standing nasal polypi could be firm and whitish due to squamous metaplasia

48. Firmness of long standing nasal polypi could also be caused by fibrosis

49. Presence of surface ulceration on the polyp should arouse suspicion of other pathologies

50. TIP Presence of thick tenaceous secretions along with Nasal polypi is caused by eosinophilic mucous chronic rhinosinusitis

52. Presence of inflammatory exudate

53. Lining mucosa is ciliated columnar epithelium. Basement membrane is thickened. The stroma contains lymphocytes

55. Chronic inflammatory nasal polypi

56. Seromucinous / glandular polypi

58. Seen in pts with allergy

59. Lined by ciliated columnar epithelium

60. Ulceration of mucosa, mucositis, epithelial hyperplasia and squamous metaplasia may be seen

61. Basement membrane is thickened, submucosa is oedematous. Mucous retention cyst+

62. Eosinophils / plasmacells/ lymphocytes infiltrate+

63. Allergic nasal polyp vs cystic fibrosis nasal polyp Allergic nasal polyp Nasal polyp due to cystic fibrosis Thick basement membrane Thin basement membrane Stroma contains predominat eosinophils Stroma contains predominantly neutrophils Mucous secretions thin Mucous secretion thick

65. This type is less common

66. May be caused when oedematous polypi are traumatized

67. Stroma may show secondary inflammatory change

68. Stroma may show myofibroblastic proliferation

69. Submucosal fibrosis +

70. Squamous metaplasia +

72. This type of nasal polyp is rare

73. This is a true neoplasm

74. Underlying bone remodelling can also be seen

76. Nasal and choanal components are solid

77. Lined by pseudostratified columnar epithelium

78. Basement membrane appears thinned out

79. Stroma shows evidence of myxoid degeneration

80. Inflammatory cells are few in number

81. Degenerative changes are common

82. Thank you