Pediatric Lung Diseases

Question 1

Entire bronchial tree is developed by […] gestation.

Answer 1

16 weeks

Question 2

Alveoli mostly form […].

Answer 2

after birth (begin forming at 37 weeks gestation).

Question 3

Arterial development […] bronchial dvelopment.

Answer 3

lags behind

Question 4

5 Important Growth Periods of the Embryonic Lung

Answer 4

1. Embryonic (4th-7th weeks): Lung development begins as protrusion from foregut, which undergoes early branching into main and segmental bronchi.
2. Pseudoglandular (7th-16th weeks): Smaller airways develop.
3. Canalicular (16th-26th weeks): Acini develop, and vascularity increases.
4. Saccular (26th-36th weeks): Development of saccules (primitive alveoli) occurs, and surfactant first appears.
5. Alveolar (37th week +): True alveoli form and grow

Question 5

Respiratory Distress Syndrome Definition

Answer 5

Respiratory distress syndrome (RDS) is a clinical syndrome characterized by respiratory dysfunction in infants, caused by deficiency of pulmonary surfactant. It was formerly known as “hyaline membrane disease” and that term is still commonly used by some physicians.

Question 6

Respiratory Distress Syndrome

Answer 6

1. Usually in premature infants.
2. Diabetes and cesarean section are risk factors.
3. Infant is OK at birth, but develops progressive respiratory distress within minutes to a few hours after birth.
4. Infiltrates on chest film.
5. If premature birth cannot be prevented, its severity can be reduced by antenatal steroid treatment to the mother (to accelerate maturation of type II pneumocytes in fetal lungs).
6. After birth, treatment includes administration of artificial surfactant and respiratory support; many survive without sequelae.

Question 7

Pathogenesis of RDS

Answer 7

deficiency in surfactant due to pulmonary immaturity

Question 8

Pathology of RDS

Answer 8

atelectasis and hyaline membranes in the lungs

Question 9

Complications of RDS

Answer 9

1. Patent ductus arteriosus.
2. Interventricular hemorrhage of brain (due to hypoxia).
3. Necrotizing enterocolitis.
4. Oxygen toxicity to lungs.
5. Bronchopulmonary dysplasia.

Question 10

Bronchopulmonary Dysplasia

Answer 10

1. Chronic neonatal lung disease complicating unresolved RDS, causing persistent respiratory distress.
2. Before surfactant therapy became available in the 1980s, the “old” form of BPD was caused by barotrauma (too much ventilatory pressure) and oxygen toxicity (too much oxygen); this is very rare now.
3. “New” form of BPD in modern era results from disrupted lung development and alveolar hypoplasia (fewer and larger alveoli); the cause is poorly understood.
4. May last for months to years or cause death.
5. Pathology is persistent lung immaturity; chronic atelectasis, alveolar hypoplasia, and interstitial fibrosis may be seen.

Question 11

Congenital Anomalies

Answer 11

1. Bronchogenic (foregut cysts)
2. Sequestrations
3. Pulmonary Hypoplasia

Question 12

Bronchogenic Cysts

Answer 12

pinched-off remnants of primitive esophagobronchial tissue that form a benign cyst in the lung, mediastinum, or next to the gut.

Question 13

Sequestrations

Answer 13

portions of lung without a bronchial connection and with a systemic arterial (aortic) blood supply. Intralobar sequestrations are located within the visceral pleura (within one of the lungs), most commonly in the posterior segment of the left lower lobe. Extralobar sequestrations are invested by their own pleura, and are separate from the lungs; these may be in the thorax, but occasionally form in the abdomen beneath the diaphragm

Question 14

Pulmonary Hypoplasia

Answer 14

is a condition characterized by underdevelopment of a lung, which largely lacks acinar development and typically is 1/2 normal size. Causes include:

a. External compression (rib cage anomalies, diaphragmatic hernia).
b. Renal agenesis or disease (Potter syndrome).
c. Oligohydramnios (decreased amniotic fluid).
d. Anencephaly.
e. Idiopathic.
f. Association with many complex malformation syndromes.

Question 15

Cystic Fibrosis Definition

Answer 15

A multisystem genetic disease caused by abnormal transport of chloride across epithelial cell membranes, resulting in thickened, viscous secretions, which affects the lungs, digestive system, sweat glands, and reproductive organs.

Question 16

CF is the most common “life shortening” […] genetic disease among […] populations.

Answer 16

Most common “life-shortening” autosomal recessive genetic disease among Caucasian populations.

Question 17

CF is a widespread disorder of […] of all […] glands.

Answer 17

CF is a widespread disorder of secretory process of all exocrine glands.

Question 18

CF is a defect in the regulation of […].

Answer 18

CF is a defect in the regulation of epithelial chloride transport (chloride channels).

Question 19

CF Genetics

Answer 19

• Gene is on chromosome 7, which encodes the CFTR protein (cystic fibrosis transmembrane conductance regulator), a transmembrane protein that regulates transport of chloride across cell membranes.
• Over 200 mutations; most common (70%) mutation is delta F508 (deletion of 3 DNA bases coding for phenylalanine at amino acid residue position 508)

Question 20

Major symptoms of CF

Answer 20

Major symptoms are due to pancreatic insufficiency and repeated respiratory infections.

Question 21

Diagnosis of CF

Answer 21

Diagnosis usually includes sweat chloride test or genetic testing

Question 22

CF Pulmonary Changes

Answer 22

Pulmonary changes are airway-based: mucous plugging, chronic bronchitis, bronchiectasis, and obliterative bronchiolitis.

Question 23

Bacterial infections and CF

Answer 23

Secondary bacterial colonization of abnormal airways is essentially universal at an early age, and chronic bacterial infections are common, especially with Pseudomonas aeruginosa; these infections may be extr

Question 24

Bronchiectasis Definition

Answer 24

Fixed dilatation of large airways (bronchi), usually due to a previous necrotizing inflammatory process in the airways resulting in permanent airway scarring.

Question 25

Causes of Bronchiectasis

Answer 25

1. Bronchial obstruction: Airways distended with secreted mucus, infection develops, and change is permanent if obstruction is not relieved.
2. Congenital or hereditary conditions: Numerous congenital conditions can result in bronchiectasis. The classic example is cystic fibrosis, causing repeated airway infections (especially with Pseudomonas) and secondary bronchiectasis.
3. Immunodeficiency states: Again a result of repeated airway infections.
4. Ciliary abnormalities: Patients with defective ciliary action are more prone to retention of mucus and repeated infections of the airways, leading to bronchiectasis. A host of ciliary abnormalities have been identified. Typically, the defect is an autosomal recessive trait that involves the whole body. Primary ciliary dyskinesia (Kartagener syndrome) is the prototypical example, characterized by defects in ciliary structure and function, leading to bronchiectasis, sinusitis, and situs inversus.
5. Necrotizing bronchopneumonia: Bronchiectasis can result as a secondary abnormality following severe infections, especially pertussis; fortunately this is no longer common.

Question 26

Pathology of Bronchiectasis

Answer 26

• Gross pathology: Airways are dilated compared to normal and are typically thin-walled; may be symmetrically dilated or saccular.
• Microscopic pathology: Airway dilatation, absence of normal bronchial wall structures (glands, muscle, cartilage), fibrosis and chronic inflammation of airways, and sometimes superimposed acute infection.
• Clinical course: Chronic productive cough, occasional hemoptysis, episodes of acute infection, and eventually cor pulmonale (right heart failure) and cyanosis. Clubbing of the fingers is common.

Question 27

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Question 29

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Question 30

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Question 31

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Question 32

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Question 33

Potter’s Syndrome

Answer 33

•lung hypoplasia with renal:

• agenesis (no kidneys)
• dysplasia (abnormally formed kidneys)
• infantile polycystic disease

Question 34

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Question 35

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Question 36

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Question 37

Kartagener’s Syndrome

Answer 37

• Triad of situs inversus, bronchiectasis, and sinusitis
• Cilia are immotile or dyskinetic
• Autosomal recessive trait
• Males are infertile

Question 38

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Question 39

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