(14.1) Pulmonary Pathology (Singh) Flashcards by Jaime Weber

Describe the progression of normal fetal lung development

Embryonic (lung bud) –> Pseudoglandular –> Canalicular –> Saccular –> Alveolar

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What are the clinical uses for knowing the stage of fetal lung development?

Knowing the stage can help the clinician determine the age of the fetus

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What are the requirements for normal fetal lung development?

Space in the thoracic cavity
Ability to inhale (chest call must be able to move, and there must be enough material (amniotic fluid) present to inhale

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What are the main structures you will see histologically of the trachea and main bronchi?

Cartilage

Glandular tissue

Respiratory epithelium

Smooth muscle layer

Lamina propria

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Describe what you would encounter with a low-power image of lung parenchyma

Alveoli

Blood vessels

Bronchioles

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Describe what you would encounter with a high-power image of lung parenchyma

Erythrocytes

Macrophages

Type 1/2 pneumocytes

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What is CRUCIAL to the sucessful oxygen exchange occuring in the lungs?

A very THIN layer between the circulating erythrocytes and alveolar lumen

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Describe the function of Type I pneumocytes

Facilitate gas exchange

*Support and line the alveoli

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Describe the function of Type II pneumocytes

Product surfactant

Replace type 1 pneumocytes

***THEY ARE MODIFIED STEM CELLS HOW COOL IS THAT WOWOWOW

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What is the function of alveolar pores?

Allow aeration but also bacteria/cells/exudate to travel between alveoli

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What is this pathology?

Pulmonary hypoplasia

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What causes pulmonary hypoplasia?

Reduced space in the thoracic cavity (eg. diaphragmatic hernia)

Impaired ability to inhale (eg. oligohydraminos, airway malformation, chest wall motion disorders)

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What is the mortality rate of pulmonary hypoplasia?

HIGH! (up to 95%)

If lung weight is <40%, immediate death occurs in neonatal period

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What are foregut cysts?

Detached outpouchings of foregut

Seen along hilum and mediastinum

Can be respiratory, esophageal or gastroenteric

Often seen incidentally; complications include rupture, infection, or airway compression

Tx: Excision is curative

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What is congenital pulmonary adenomatoid malformation (CPAM)?

“Arrested development” of pulmonary tissue with formation of intrapulmonary cystic masses

aka, a specific type of pulmonary tissue decides to only make a certain type of tissue for the rest of it’s life

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What are pulmonary sequestrations?

Nonfunctioning lung tissue that forms as an aberrant accessory“lung bud”

*Typically found in the region of the left lower lobe

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How are pulmonary sequestrations characterized?

Lack of connection to the tracheobronchial tree

Independent (systemic) arterial supply

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What is this image an example of?

Intralobar pulmonary sequestration (ILS)

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What are intralobar pulmonary sequestration (ILS)s susceptible to?

Lack of airway perfusion makes ILS’s susceptible to infection and absess formation

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What is this an example of?

Extralobar pulmonary sequestrations (ELS)

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How are extralobar pulmonary sequestrations (ELS) different from ILS?

ELS have their own PLEURA

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What comes to attention sooner…

ILS or ELS?

ELS

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Describe the differences between these congenital anomalies:

CPAM/CCAM

Pulmonary sequestraion

CPAM/CCAM = INTRApulmonary cystic malformation w/ CONNECTION to tracheobronchial airways and pulmonary vasculature

Pulmonary sequestration = INTRA or EXTRA pulmonary lung tissue with NO CONNECTION to pulmonary vasculature or tracheobronchial tree

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What is atelectasis?

Partial or complete collapse of the lung

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What are the three major types of **atelectasis?**

- Resorption - Compression - Contraction

What causes **resorption atelectasis?**

**Airway obstruction** with gradual _resorption_ of air reduces lung expansion

What causes **compression atelectasis?**

**Accumulated material** in pleural cavity **compresses** the lung parenchyma

What causes **contraction atelectasis?**

**Fibrotic** or other **innate restrictive process** in the pleura or peripheral lung restricts lung expansion

What is the LEAST common form of **atelectasis?**

Contraction atelectasis

What pathologic process is occuring here?

Pulmonary edema

What are the major causes of **pulmonary edema?**

"Pushing out" --\> left sided heart failure "Leaking out" --\> liver disease Injury to alveolar wall

What are the clinical criteria for **acute lung injury (ALI)?**

Acute onset Hypoxemia Bilateral infiltrates No evidence of cardiac failure

What is the clinical criteria for **acute respiratory distress syndrome (ARDS)?**

Worsening hypoxemia

What is **diffuse alveolar damage (DAD)?**

Histologic manifestation of ARDS

What is the pathology?

Acute respiratory distress syndrome (ARDS)

What are the clinical indications of **acute respiratory distress syndrome (ARDS)?**

- Abrupt obsent of symptoms - Hypoxemia (PaO2/FiO2) \<200 - Bilateral infiltrates - Non-cardiac in nature

What is the pathology?

Diffuse alveolar damage (DAD) Edema + Fibrin + Cell debris = HYALINE MEMBRANES

Describe the histologic differences b/w a normal lung and a lung w/ hyaline membranes

Lung w/ hyaline membranes has THICKENED walls that make oxygen exchange nearly impossible This is what accounts for the decreased PaO2/FiO2 values observed

What are the three stages of ARDS?

1. Exudate 2. Proliferative 3. Fibrotic

What occurs during the **exudative stage** of ARDS?

Edema Hyaline membranes Neutrophils

What occurs during the **proliferative stage** of ARDS?

Fibroblast proliferation Organizing pneumonia Early fibrosis

What occurs during the **fibrotic stage** of ARDS?

Extensive fibrosis Loss of normal alveolar architecture

ARDS : resolution After the fibroproliferative phase, 2 pathways may ensue... what are they?

Resolution OR Fibrosis (irreversible)

What is **acute interstitial pneumonia (AIP)?**

Same clinical presentation as **ARDS** Same histology as **ARDS/DAD** **_\*\*\*CANNOT BE ATTRIBUTED TO A SPECIFIC ETIOLOGY_**

What is a **restrictive lung disease?**

Volume restriction FEV1/FVC is normal **FVC is reduced** (FEV=force expiratory volume, FVC=forced vital capacity)

What is **obstructive lung disease?**

Decreased flow **LOW FEV1/FVC ratio** \*\*\*(FEV=force expiratory volume, FVC=forced vital capacity)

What are examples of **obstructive pulmonary diseases?**

Emphysema Chronic bronchitis Asthma

What is the most common cause of **COPD/Chronic bronchitis?**

Smoking

Describe what is occuring during a **chronic bronchitis** state

- Mucus hypersecretion - Inflammation - Infection \*Typically is a response to **cigarrette** **smoke**

# Define: Chronic bronchitis

Persistent cough **w/ sputum production** for _3 months out of 2 consecutive years_

What is the predominant pathophysiologic mechanism of chronic bronchitis?

Mucous gland **hyperplasia**

What is the pathology?

Emphysema \*Notice the extremly dilated spaces within the lung parynchema

Why is **emphysema** considered an _obstructive process?_

There is a **compressed duct** proximal to the alveolar sac

What is the clinical presentation of **emphysema?**

Enlarged lungs on CXR "Barrel chest" FEV1/FVC ratio is reduced

What does "blue bloaters" refer to?

Chronic bronchitis

What does "pink puffers" refer to?

Emphysema

What is alpha1-antitrypsin?

Alpha1-antitrypsin coats the lungs **protecting** them from **neutrophil elastase** Neutrophil elastase is produced by white blood cells to break down harmful bacteria

What is an **alpha1-antitrypsin deficiency?**

Lungs LACK alpha1-antitrypsin coating This leaves lungs **vulnerable** to damage by **neutrophil elastase**

Describe the type of emphysema associated with each image

Alpha1 antitrypsin deficiency demonstrates a ___________ emphysema pattern

BASILAR panacinar

What are the basic mechanisms of **asthma?**

What are the classifications of **asthma?**

Atopic (extrinsic) Non-atopic (intrinsic)

Describe **atopic** asthma

2/3 of all patients May be any age, usually children FH of asthma Elevated **IgE levels** (type I hypersensitivity) Triggers may include a variety of **allergens**

Describe **non-atopic** asthma

1/3 of all patients Often older pts NORMAL IgE levels Triggers include **cold, exercise, infection**

Why is it SO important to make sure your asthmatic patients' have "controlled" asthma?

High potential for irreversible **airway remodeling**

What are some of the results of **airway remodeling?**

Fibrosis Smooth muscle hyperplasia Increased goblet cells and submucosal glands

Pharmacologically, what is a huge problem in patients that have undergone airway remodeling?

DECREASED response to therapeutic agents: Bronchodilators Corticosteroids

What is **status asthmaticus?**

Unremitting, potentially fatal asthma attack Characterized by **bronchial occlusion by thick mucus** \*Hallmark = **_curschmann spirals_** (coiled mucus plugs)

What is **aspirin-sensitive asthma?**

Unique sensitivity to aspirin that induces asthma Highly associated with: nasal polyps and recurring rhinitis

What is **bronchiectasis?**

**Necrotizing inflammatory response** that is an end stage process of multiple processes that can include infection or obstruction

Describe the path of **cystic fibrosis**

CFTR gene is affected Chloride transport is affected W/out it, cells absorb extra Na+ and H20 --\> Leads to dehydrated mucus

What is **kartagener's syndrome?**

Aka Primary ciliary dyskinesia --\> Dysfunction of **_dynein arm_** of microtubules Triad of : Sinusitis, bronchiectasis, situs inversus \*\*\*Often male infertility

What is this pathology?

Allergic Bronchopulmonary Aspergillosis (ABPA)

What is **allergic bronchopulmonary aspergillosis (ABPA)?**

Exaggerated hypersensitivity response to **Aspergillus** infection overlying chronic lung disease --\> Background of **asthma** or **CF** -Increased **IgE** on serum testing, positive **skin test** \*\*\*Thick mucus in bronchi