Nasalpolyp pathology

This presentation discusses the topic "Pathology of nasal polyp"

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Pathology of nasal polyp
Dr T Balasubramanian

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Introduction
Macroscopically polyp appears to arise like a pedicled
tissue from the nasal mucosa
Histopathologically these polyp can be very diverse
ranging from simple inflammatory to bening /
malignant neoplasm
Polyp due to chronic rhinosinusitis can be described as
non granulomatous inflammatory tissue projecting
from the nasal mucosa

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Histology of normal sinonasal mucosa
1
Components of normal sinonasal mucosa can be
categorized under two heads (Structural / Non
structural) components
Structural components – Surface epithelium, basement
membrane and submucosal tissue
Non structural components – Resident / Non resident
cells of lymphoid / Myeloid origin

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Histology of normal sinonasal mucosa
Epithelium
Anterior 2 cm of nasal cavity is lined by skin i.e.
Keratinized stratified squamous epithelium with
fibrocollagenous dermis and adnexal glands
The rest of the nasal cavity is lined by respiratory type
of epithelium (Schneiderian membrane)
The lining mucosa of paranasal sinuses is rather thinn
when compared to that of nasal cavity

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Schnederian membrane
Sinonasal mucosa is also known as Schnederian
membrane
It is composed of 4 cell types – ciliated columnar /
cuboidal cells, interspaced goblet cells, nonciliated
columnar cells with microvilli and basal cells
The ratio of columnar : goblet cells is 5:1
Columnar epithelium contains tight junctions and rest
on the basement membrane
Squamous metaplasia is common due to exposure

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

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Basement membrane
The basement membrane contains following collagen
types (I, III, IV, V, VI, & VII)
Other constituents include: Heparan sulfate
proteoglycan, laminin and Nidogen
The basement membrane is thin and delicate in the
whole of nasal cavity except for inferior turbinate
area.

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Olfactory epithelium
Responsible for the sense of smell
Lines superior turbinate, superior portion of nasal
septum, roof of nasal cavity and medial portions of
middle turbinate
This epithelium is also pseudostratified ciliated
columnar containing bipolar olfactory cells,
microvillar cells and supporting sustentacular cells

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

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Submucosa
Lies under the basement membrane
Overlies the cartilagenous / bony framework of nasal
cavity
Contains loose fibrovascular connective tissue,
seromucinous / minor salivary glands, blood vessels,
nerves, myeloid and lymphoid cells
Blood vessels contains many av anastomosis
Blood vessels communicate with venous erectile
tissue which are prominent over inferior turbinates

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Non structural components
Lymphoid tissue is the most important of these
components
Components of lymphoid tissue include single
lymphocytes scattered among the epithelial cells and
lamina propria and NALT

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NALT
Acronym for Nasal associated lymphoid follicles
Similar to Payer's patch of intesting
Unencapsulated
Becomes enlarged during nasal infections

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Lymphoid cells of nasal cavity
T cells
B cells
Plasma cells
Natural Killer cells

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Causes of nasal polyp
Chronic rhinosinusitis (still not proved)
Samter's triad (Bronchial asthma, aspirin
hypersensitivity and nasal polyposis)
Eosinophilic chronic rhinosinusitis including AFRS
Cystic fibrosis
Young's syndrome
Churg – Strauss disease

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Macroscopic features
Pale smooth shining and oedematous mass
Soft in consistency when compared to surrounding
nasal mucosa
Long standing nasal polypi could be firm and whitish
due to squamous metaplasia
Firmness of long standing nasal polypi could also be
caused by fibrosis
Presence of surface ulceration on the polyp should
arouse suspicion of other pathologies

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

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Microscopic feature of nasal polypi
Structural changes involve lining epithelium,
submucosa and rarely underlying bone / cartilage
Presence of inflammatory exudate
Lining mucosa is ciliated columnar epithelium.
Basement membrane is thickened. The stroma
contains lymphocytes

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Histological classification
Oedematous allergic nasal polypi
Chronic inflammatory nasal polypi
Seromucinous / glandular polypi

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Oedematous allergic nasal polypi
Commonest variety
Seen in pts with allergy
Lined by ciliated columnar epithelium
Ulceration of mucosa, mucositis, epithelial
hyperplasia and squamous metaplasia may be seen
Basement membrane is thickened, submucosa is
oedematous. Mucous retention cyst+
Eosinophils / plasmacells/ lymphocytes infiltrate+

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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 eosinophilsStroma contains predominantly
neutrophils
Mucous secretions thin Mucous secretion thick

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Chronic inflammatory polyp
Also known as fibroinflammatory polyp
This type is less common
May be caused when oedematous polypi are
traumatized
Stroma may show secondary inflammatory change
Stroma may show myofibroblastic proliferation
Submucosal fibrosis +
Squamous metaplasia +

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Seromucinous polypi
Caused by hyperplasia of seromucinous glands
This type of nasal polyp is rare
This is a true neoplasm
Underlying bone remodelling can also be seen

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Histology of A/C polyp
Antral component is soft and cystic
Nasal and choanal components are solid
Lined by pseudostratified columnar epithelium
Basement membrane appears thinned out
Stroma shows evidence of myxoid degeneration
Inflammatory cells are few in number
Degenerative changes are common

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