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Upper Respiratory Tract (URT)

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Vadim Kurbatov

on 22 February 2014

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Transcript of Upper Respiratory Tract (URT)

Bacterial Rhinitis
"Common Cold"
Common pathogens:
adenovirus, echovirus and rhinovirus

Symptoms:
scant stringy discharge, edematous, erythematous nasal mucosa; enlarged turbinates

Viral Rhinitis
Keep an index of suspicion for obstruction when you see something like this on exam: kid's love to hide things in their noses
- thick mucous
- pus (dead epithelial cells, neutrophils, and bacteria
- can be secondary to viral rhinitis
Viral rhinitis is the most common cause of "cold" symptoms. Since the etiology is viral, antibiotics are not indicated! Overuse of antibiotics in people with common colds is a problem. Treatment should be supportive and aimed at symptom relief (i.e. rest, avid hydration, antipyretics for fever)
Upper Respiratory Tract (URT)
Highlights from Nasal Cavity
Includes openings for the auditory tubes (a.k.a. eustacian tubes)
Lined by
stratified squamous epithelium
(inferior anterior and posterior walls and anterior lateral walls) and
respiratory type epithelium
(around nasal choanae and roof of posterior wall)
Remaining areas have mixtures of squamous and respiratory or
intermediate epithelium

Intermediate epithelium is usually concentrated as a wavy ring at junction of nasopharynx and oropharynx
Abundant lymphoid tissue present
Highlights from Nasopharynx
Paranasal Sinus Highlights


Sinuses are diverticula of nasal cavity that extend into neighboring bones

Ethmoid sinuses:
between the orbits; well developed at birth
Frontal sinuses:
most anterior, above the orbits; small/rudimentary at birth; develop through puberty
Maxillary sinuses:
under the cheeks; small/rudimentary at birth; develop rapidly during childhood until permanent teeth develop
Sphenoid sinuses:
most posterior at base of brain; small/rudimentary at birth; develop rapidly during childhood until permanent teeth develop


Mucosa is continuous with nasal cavity and similar (respiratory type epithelium)
Thinner and less vascular
Fewer goblet cells and seromucinous glands than nasal cavity
Normally no lymphoid tissue
With chronic irritation, such as with recurrent allergic reactions, the number of goblet cells may increase, leading to increased mucous production.


Acute Allergic Rhinitis
Relatively common life-threatening fungal infection, associated with diabetic ketoacidosis, poor glycemic control or immunosuppression
Spreads rapidly across nerves and tissue planes to blood vessels of orbit and brain, causes thrombosis, hemorrhage and infarction
Member of phylum Zygomycota, class Zygomycetes, order Mucorales; found in high-organic matter and soil
Mortality rate of 48%
Case reports: 29 year old man post bone marrow transplant with psychosis and gingival lesion
Fungal hyphae filling vascular lumen and infiltrating vascular wall
CASE
25 year old medical student started his pediatric clerkship 2 weeks ago. He reports that he has had a runny nose for the last few days. He has not had fevers, sore throat, cough or any other symptoms

Diagnosis: Viral Rhinitis

Rhinitis Defined:
Inflammation of the nasal cavity
– Can be allergic or infectious
– Symptoms include runny/stuffy nose (from excessive mucous production in response to stimulation of an inflammatory process)
Outline of this Presentation
1. Histology overview (what's a mucosa?)
2. Deeper look into histology of the
a. Nasal Cavity
b. Nasopharynx
c. Paranasal sinuses
In each space, we will discuss the relevant anatomy and histology and provide clinical examples of pathology and histopathology.


Olfaction
Filters air
Humidifies/warms air
Decrease density of head (makes it easier to hold your head up!)
Air space to increase resonance of voice
Protection against pathogens! (The point of this module)
Cosmetic?
What does the nasal/sinus mucosa do?
Histology Overview!
Epithelium and underlying connective tissue (
Lamina Propria
)
The lamina propria – lots of
small capillaries and small seromucous glands
to help in heating and humidification of inspired air
Mucous
and
IgA
are also produced in Lamina propria, which help to trap particles/gunk from entering the lower respiratory tract

What's a mucosa?
What's an Epithelium?
The entire respiratory tract is lined by a layer of cells called the
mucosal epithelial lining
The epithelial lining acts as the first line of defense against foreign pathogens
Physical barrier
Secretes mucous that traps particles
Oversecretion can be pathologic
Secrete antimicrobial peptides (
Defensins
) to interrupt microbial cell membranes

Typical structure of respiratory epithelium

Ciliated Pseudistratified columnar epithelium
Pseudostratafied means that all cells touch the basement membrane
Consists of 5 cell types:
Ciliated columnar cells
Goblet cells
Brush Cells
Small granule cells (Kulchitsky cells)
Basal Cells

Compare:

Nose – respiratory epithelium vs specialized olfactory epithelium
Sinuses – fewer mucous secreting cells, thinner epithelium
Pharynx – respiratory epithelium, mucosa contains tonsils and openings to auditory tubes
Auditory tube – lined with ciliated pseudostratified epithelium (Like the rest of the URT). Upon entering the Middle Ear, epithelium transitions to simple cuboidal cells


Histology varies depending on location

Mucociliary Escalator
Why is the respiratory mucosa ciliated?
Muco
- mucous, produced by goblet cells, traps foreign/large particles
Ciliary
- cilia on the epithelium push these trapped particles up and out!
works in tandem with other mechanisms (cough and sneeze reflexes) to get things out)
more: http://www.colorado.edu/outreach/BSI/k12activities/interactive/actidhpamucociliary.html
More Resources
Here are some links to tutorials on the different layers of the nasal and sinus mucosa:

http://www.getbodysmart.com/ap/respiratorysystem/nose/nasalmucosa1/tutorial.html

http://www.getbodysmart.com/ap/respiratorysystem/nose/sinuses/tutorial.html
Primary Ciliary Dyskinesia (PCD)
Proper ciliary function is essential for normal physiologic function
In PCD, a genetic mutation in the dynein protein, a necessary component of cilia, results in dysfunction
Without adequate ciliary clearance, patients are prone to recurrent URT infections.
Called Kartagener's syndrome when associated with
Bronchiectasis
Infertility
Situs Inversus
**Key point: In order to infect us, pathogens MUST break through the protective epithelial barrier!

Our respiratory epithelium is usually intact and will protect against foreign invaders, but any cut/abrasion/laxity in the integrity of the epithelial lining can allow entry of a pathogen and lead to a subsequent host response
Divided into olfactory region (superior nasal turbinates and opposed septum) and respiratory region (rest of cavity)
Nasal chambers are on either side of median plane formed by nasal septum
Bounded above by cribriform plate; bounded laterally by turbinates
Bulla ethmoidalis: elevation on lateral wall of middle meatus, site of opening of middle ethmoid meatus
Choanae: posterior opening of nasal cavity, communicates with nasopharynx
Columella: anterior extreme nasal septum
Nares: anterior openings of nasal cavity
Vestibule: slight dilation inside anterior aperture of nostril, bounded laterally by ala and lateral crus of greater alar cartilage and medially by medial crus of greater alar cartilage; lined by skin containing hair and sebaceous glands
Lateral wall: contains superior, middle and inferior nasal turbinates (conchae); below each is corresponding nasal passage or meatus
Sphenoethmoidal recess: above superior turbinate, site of opening of sphenoidal sinus
Turbinates (concha): comprise lateral walls of each nasal cavity
Superior meatus: along upper border of middle turbinate, site of opening of posterior ethmoid meatus
Middle meatus: below and lateral to middle turbinate

The paranasal sinuses also allow for access to more internal cranial and intracranial structures, such as the pituitary gland!
Histology of the Nasal Mucosa
The nasal mucosa contains both respiratory and olfactory epithelium
Respiratory epithelium is a pseudostratefied squamous epithelium containing goblet cells
Olfactory epithelium:

A 30 year old woman has been complaining of fevers, runny nose, headache, facial tenderness and malaise for the past 2 weeks. Her doctor recommended drinking fluids and did not prescribe antibiotics, however, her symptoms persisted.
Diagnosis: This patient shows classic symptoms of acute sinusitis. Though this is usually due to a viral infection, it may also be caused by bacteria, namely,
H. Influenzae, S. pneumoniae, moraxella catarrhalis
Case: a 50 year old male with a history of type 1 diabetes presents with fever, altered mental status and headache. He has had symptoms for the past 5 days, but has acutely worsened. He ran out of insulin 2 weeks ago. On exam, you note purulent discharge from the left eye and erythema of the left cheek. When you check his finger stick glucose, it is measured to be 412
Case: a 9 year old previously healthy boy presents with a 3 days history of sore throat and fever. He does not have a cough or runny nose. On exam, you note that he has enlarged tonsils with exudates and enlarged cervical lymph nodes. Pharynx appears erythematous.
Diagnosis: Group A Strep Pharyngitis

ddx: mononucleosis - EBV infection
viral pharyngitis

fig 1
fig 2
media 1
fig 3
What Can Go Wrong?

Infection in two common flavors:
Viral or Bacterial
Allergy
Obstruction (i.e marbles/quarters)
Other:
Cancer
Leprosy
Polyps (Allergic of Cystic Fibrosis)
Granulomas
Common allergens:
plant pollens, fungi, animal dander, and dust mites.
-IgE mediated type I hypersensitivity
-Eosinophilic infiltration of mucosa
-Signs: Marked mucosal edema, redness, thick mucus secretion, pale turbinates
- Watery discharge
Unique Aspects of Histology
Case
Sinus Development and Location:
Unique Histology
This CT scan of the chest shows extensive bronchiectasis. This image scans superior to inferio and as the slices descend, you can see marked areas of dilitation in the lungs. These are prone to infection and patients will often present with "cupfulls" of sputum
Situs Inversus
This is an endoscopic view of the healthy nasal cavity. The scope is inserted through the nares and traverses through the nasal cavity, showing healthy nasal mucosa covering the turbinate bones laterally, and nasal septum medially. Note that the mucosa is pink, smooth, uninflamed, and shiny without any excess mucous.
But first, lets review the relevant anatomy
Chronic Sinusitis
Recurrent inflammation of the paranasal sinuses leading to abundant mucous buildup. Patients may benefit from surgical intervention.
These videos show endoscopic drainage of impacted maxillary sinuses from chronic sinusitis. The video on the left is shorter and describes the relevant anatomy. Video on the right is longer and much more disgusting :)
This is a CT scan of the head from scanning from anterior to posterior. The paranasal sinuses (including maxillary, ethmoid air cells, sphenoid sinus, frontal sinuses and mastoid air cells) can be visualized in this manner.
Anatomy Review
Another Horrible Disease
Mucormycosis

Sinusitis defined
: Inflammation of the sinuses

If the allergic or infectious offender enters the sinus, the same inflammatory reaction can cause mucous buildup in the sinuses. Mucous may block the ostia that allows drainage, causing facial pain and congestion
(zoom into this tiny box if you want a description of the nasal cavity) --->
Differential Diagnosis for runny nose
You can see exudates on the tonsils and the mucosa looks injected/erythematous (these just mean "red")
(An aside)
Case
A 54 year old man who immigrated from China 10 years ago presents with a 2 month history of nasal congestion and complaints of a mass in the neck. He has smoked 1 pack of cigarettes/day for 30 years On exam, he is found to have cervical lymphadenopathy and a mass extending into his nasal mucosa. EBV titers are sent and return positive
Diagnosis: Nasopharyngeal Carcinoma
Unlike the nasal mucosa, which contains predominantly pseudostratefied columnar epithlium, the nasopharynx houses many types of epithelium including squamous epithlium, pseudostratefied columnar epithelium and transitional. All of these may be involved in a neoplasm. EBV infection is the most commonly associated risk factor for developing nasopharyngeal carcinoma. Smoking, heavy drinking and certain diets are also linked to this cancer. The Asian diet is particularly implicated as it is high in salt-cured fish and meat. This type of cancer is rare in the United States, but incidence is much higher in Asia.
Wrap-up
Of course this module does not nearly cover the entire differential for pathology in the upper respiratory tract. This is meant to provide examples of the types of histologic changes that can occur when disease strikes these air passages.
Full transcript