The nasal cavity and paranasal sinuses have pseudostratified kinociliated columnar epithelium with goblet cells.
The nasopharynx has different epithelia in different parts
- Lower and posterior regions have non-keratinizing stratified squamous
- Near the choanae is the epithelium pseudostratified kinociliated columnar epithelium with goblet cells
The epiglottis and true vocal cord have non-keratinizing stratified squamous epithelium.
The false vocal cord, ventricle and subglottis has pseudostratified kinociliated columnar epithelium.
The upper respiratory tract involves the nasal cavity, pharynx and larynx. The most common causative pathogens for upper respiratory tract infections are:
- Influenza virus
- Haemophilus influenzae
These pathogens cause rhinitis, sinusitis and laryngitis.
Rhinitis and sinusitis describe the inflammation of the nasal cavity or paranasal sinuses respectively. They mostly occur together as rhinosinusitis. It causes symptoms of sneezing, congestion and runny nose, exactly the same as your typical common cold. Hypersecretion of mucus and oedema of the mucosa are what causes the nasal and sinusal obstruction.
Several subtypes exist:
- Allergic rhinitis
- Infectious rhinitis
- Viral rhinitis
- Bacterial rhinitis
Allergic rhinitis or hay fever is the most common cause of rhinitis in adults. It’s a hypersensitivity type I reaction that occurs following exposure to an allergen, like pollen, dust mites, cat hair and so on. Histology of the mucosa shows submucosal oedema, with primarily eosinophilic infiltration.
Infectous rhinitis is most commonly viral, in which case it’s called the common cold. It is often self-limiting, but it can rarely progress into chronic rhinitis. Bacterial rhinitis is more prevalent in immunocompromised people and people who already have viral rhinitis. There is mucopurulent exudate. Repeated acute rhinitis can lead to chronic rhinitis, where the mucosal surface becomes ulcerated.
Acute sinusitis can be a complication of any rhinitis. Recall from anatomy that the maxillary sinus isn’t easily drained, so an empyema inside the maxillary sinus may form. It may progress into chronic sinusitis. Chronic sinusitis may spread to the bone or dural venous sinuses, causing osteomyelitis or thrombophlebitis respectively.
Chronic rhinitis or sinusitis can lead to polyps. They aren’t neoplastic polyps, but are rather formed by swelling of the mucosa. They can also occur due to allergy or cystic fibrosis. These polyps can become ulcerated or metaplastic.
Fungus ball are clumps of mold that can occur in body cavities like the paranasal sinuses. They occur due to infection by the fungus aspergillus.
Sinonasal mucormycosis is a condition caused by a species of fungus called mucor. They spread by air and especially affect diabetic and immunosuppressed patients. It’s a fungus that likes blood vessels and can cause necrosis.
Wegener granulomatosis is a vasculitis we read about in the vasculitis topic. It can affect the vessels of the nose, causing nosebleed (epistaxis), purulent sinusitis, pain and headache. It can also cause perforation of the nasal septum.
Neoplasms of nasal cavity
Schneiderian papilloma is a benign epithelial neoplasm.
Squamous cell papilloma is another benign neoplasm.
Many types of sinonasal carcinomas exist:
- Squamous cell carcinoma
- Lymphoepithelioma-like carcinoma
Some lymphomas also affect the upper airways, like DLBCL. Extranodal NK/T cell lymphoma is important to know as it may cause septal perforation similar to that in cocaine abuse.
Inflammation of pharynx
Inflammation of the pharynx often involves the tonsils. Tonsillitis is often bacterial. The tonsils become covered in a purulent exudate and they’re swollen and hyperaemic. A peritonsillar abscess is an abscess that occurs behind the tonsils. It often occurs bilaterally.
Neoplasias in the nasopharynx
Nasopharyngeal angiofibroma is a benign tumor that grows in the nasopharynx. They tend to be locally destructive, and, like the name suggests, are comprised of vessels and fibrous tissue. They should be surgically removed.
Nasopharyngeal carcinoma is a malignant tumor in the nasopharynx. Two types exist:
- Keratinizing squamous cell carcinoma
- Non-keratinizing differentiated and undifferentiated basaloid types
Inflammations of the larynx
Laryngitis is often caused by an infection of the nasopharynx that descends into the larynx. The most important symptoms are hoarseness and dry cough, due to oedema. The main risk factor is airway obstruction, which can occur if the epiglottis is swollen.
Vocal cord nodules can grow on the vocal cord, which can cause hoarseness. These are often polyps. They’re associated with overuse of the vocal cords and resolve with rest.
Acute laryngitis is commonly a viral disease that lasts for a few days. Acute bacterial laryngitis is often caused by h. influenzae.
Croup is a special type of larynx characterized by inflammation of both the larynx and the trachea. It is most commonly caused by the parainfluenza virus. It gives a characteristic “barking” cough.
Pseudomembrane formation in the larynx can be caused by corynebacterium diphteriae, but this is rare.
Chronic laryngitis can occur as a complication of one of three things:
- Gastroesophageal reflux disease
- Recurring laryngitis
Tumors of the larynx
Laryngeal papilloma is a benign tumor. They’re related to smoking and low-risk HPV infection (6 and 11).
Squamous cell carcinoma is the most common laryngeal cancer. It usually targets two populations:
- Older people who smoke
- Younger people with HPV infection
Alcohol is also a risk factor. HPV-related laryngeal cancers have better prognosis than the smoking-related cancers. Three types exist, based on their localization:
- Supraglottic type affects the supraglottic cavity.
- Glottic type affects just the glottis and is the most common
- Subglottic type affects the subglottic cavity. It’s the rarest type.
The most characteristic symptoms are hoarseness and haemoptysis. Glottic cancers give symptoms earlier than the other types, and subglottic cancers give symptoms later than the other types.
These cancers often spread into the cervical lymph nodes.
75. Pathogenesis, classification and clinicopathology of vasculitides. Vascular tumours
77. Congenital anomalies of the lungs, atelectasis, acute lung injury