Respiratory system

RESPIRATORY TRACT

UPPER AIRWAYS
Nose:
The common diseases of the nose are inflammatory, allergic conditions and neoplastic, the most common malignant tumor at the nose is:
NASOPHARYNGEAL CARCINOMA:
Primary nasopharyngeal carcinomas are often clinically occult for long periods, and present as metastases in the cervical lymph nodes radiotherapy is the standard modality of treatment .
Morphology: On histologic examination, the keratinizing and non-keratinizing squamous cell lesions resemble usual well-differentiated and poorly differentiated squamous cell carcinomas arising in other locations. The undifferentiated variant is composed of large epithelial cells with oval or round vesicular nuclei, prominent nucleoli admixed with the epithelial cells are abundant, mature, normal-appearing lymphocytes, which are predominantly T cells so give wrong old term of lympho epithelioma.

LARYNX :

the diseases of larynx also inflammatory and allergic conditions the most important neoplastic conditions of larynx is:
CARCINOMA OF THE LARYNX
a spectrum of epithelial alterations is seen in the larynx. They range from hyperplasia, atypical hyperplasia, dysplasia, carcinoma in situ, to invasive carcinoma.
tobacco smoke is the major risk factor for development of SCC of larynx.

Morphology. About 95% of laryngeal carcinomas are typical squamous cell tumors. The tumor usually develops directly on the vocal cords, but it may arise above or below the cords.

LUNGS

The most important lung diseases are:
OBSTRUCTIVE VERSUS RESTRICTIVE PULMONARY DISEASES
Depending on the pulmonary function test pulmonary diseases can be classified into two categories:
1- Obstructive diseases (OPD), characterized by an increase in resistance to airflow owning to partial or complete obstruction at any level of respiratory tract.
2- restrictive diseases (RPD), reduce expansion of the lung parenchyma, with reduce total lung capacity.
Obstructive diseases (OPD):-
- emphysema.
- Chronic bronchitis.
- Asthma.
- And bronchiectasis.
1- EMPHYSEMA
It is a condition of the lung characterized by abnormal permanent enlargement of the airspaces distal to the terminal bronchioles, accompanied by destruction of their walls and without obvious fibrosis.
MORPHOLOGY:
GROSS: voluminous lungs, large blebs or bullae may be seen.
MICROSCOPICAL: there are abnormally large alveoli separated by thin septa, there are even larger abnormal airspaces. Often the respiratory bronchioles and vasculature of the lung deformed and compressed.


2- CHRONIC BRONCHITIS:
Chronic bronchitis per se is defined clinically. It is present in any patient who has persistent cough with sputum production for at least 3 months in at least 2 consecutive years, in the absence of any other identifiable cause.
The earliest feature of chronic bronchitis is hypersecretion of mucus in the large airways, associated with hypertrophy of the submucosal glands in the trachea and bronchi, as chronic bronchitis persists, there is also a marked increase in goblet cells of small airways—small bronchi and bronchioles—leading to excessive mucus production that contributes to airway obstruction.
Morphology: Grossly, there may be hyperemia. swelling, and edema of the mucous membranes, frequently accompanied by excessive mucinous mucopurulent secretions layering the epithelial surfaces. Sometimes, heavy casts of secretions and pus fill the bronchi and bronchioles.
Microscopically :
chronic inflammation of the airways (predominantly lymphocytes)
enlargement of the mucus-secreting glands of the trachea and bronchi.
Although the numbers of goblet cells increase slightly, the major increase is in the size of the mucous glands.
The bronchial epithelium may show squamous metaplasia and dysplasia.

3- ASTHMA

it is a chronic inflammatory disorder of the airways that causes recurrent episodes of wheezing, breathlessness, chest tightness, and cough especially at night or in the early morning.

Bronchiectasis

It is a disease characterized by permanent dilation of bronchi and bronchioles caused by destruction of the muscle and elastic tissue, resulting from or associated with chronic necrotizing infections. To be considered bronchiectasis, dilation should be permanent; reversible bronchial dilation often accompanies viral and bacterial pneumonia. because of better control of lung infections, bronchiectasis is now an uncommon condition. It is manifested clinically by high fever, and expectoration of copious amounts of fouling, purulent sputum.

Morphology : grossly : On the cut surface of the lung, the transected dilated bronchi appear as cysts filled with mucopurulent secretions.
Microscopically : an intense acute and chronic inflammatory exudation within the walls of the bronchi and bronchioles, associated with desquamation of the lining epithelium and extensive areas of necrotizing ulceration, In some instances, the necrosis completely destroys the bronchial or bronchiolar walls and forms a lung abscess.
Diffuse interstitial diseases (infiltrative, restrictive):
Diffuse interstitial diseases are a heterogeneous group of disorders characterized predominantly by diffuse and chronic involvement of the pulmonary connective tissue, many of the entities are of unknown cause and pathogenesis.
In general, the clinical and pulmonary functional changes are those of restrictive rather than obstructive lung disease. Patients have dyspnea, tachypnea. inspiratory crackles, and eventual cyanosis, without wheezing.
Idiopathic Pulmonary Fibrosis
Pathogenesis. While the causative agent(s) of IPF remain unknown, The current concept is that IPF is caused by “repeated cycles” of acute lung injury (alveolitis) by some unidentified agent. “Wound healing” at these sites gives rise to exuberant fibroblastic proliferation, giving rise to the “fibroblastic foci”. Repeated cycles of injury and wound healing ultimately lead to widespread fibrosis and loss of lung function .
MORPHOLOGY:
Microscopically: Interstitial Patchy fibrosis.