CONGENITAL DISORDERS OF LUNG

EMBRYOLOGY

STAGE PERIOD

EVENTS

Embryonal 3-5 wks Formation upto lobar bronchi.

Pseudoglandular

5-16 wks

All bronchioles of conducting system develop. Formation of columnar/cuboidal epithelium.

Canalicular 16-24 wks

Differentiation of epithelium, distal acinar development.

Saccular 24-36 wks

Alveoli and terminal sacs continue to develop.

Alveolar >36 wks

Maturation

Embryonal stage

Laryngeal/tracheal Pulmonary underde

Stenosis,TOF, Tracheomalacia

Pulmonary sequ. CCAM

Bronchogenic cyst. AV Malformation CLO

• EMBRYONAL PSEUDO CANALICULAR SACCULAR ALVEOLAR

• GLANDULAR

• • 0 3 5 16 24 36

TRACHEAL ATRESIA• Very rare, associated with maternal polyhydramnious.

• C/F : Immediate and acute with severe distress, absence of cry, inability to intubate.

• Types:

Tracheal stenosis• Rare, usually acquired is more common.• Complete tracheal cartilage rings.• Focal ( 50 % ) usually lower third , genaralised ( 30 % ) ,

funnel shaped ( 20 % ).• Clinical features: Variable• Search for other anomalies of lung.• IMAGING: Radiographs: High voltage.

CT : Dynamic changes in airway.

MRI: Relationship with Vessels

images

Tracheomalacia• Malacia= Softening.

• Softening due to abnormality of cartilage and myoelastic elements.

• Associated with relapsing polychondritis, chondromalacia, MPS like hurlers and hunter syndromes, Mounier-kuhn syndrome, TOF, vascular ring.

• Clinical features: Similar to asthma like wheeze, cough, dyspnea. Expiratory wheeze increasing with cry and disappears on rest.

• Imaging:

Fluoroscopy

Dynamic CT

Bronchoscopy

Tracheal Bronchus• First described by Sandifort in 1785 as a right upper bronchus

originating from trachea.• Variety of bronchial anomalies arising from trachea or main

bronchus directed towards upper lobe territory.• Two types : Displaced

Supernumerary : Tracheal diverticula.

Apical accessory lungs or tracheal lobes.• When the entire upper lobe bronchus is displaced on

trachea, it is also called as “pig bronchus”.• Clinical features: Asymptomatic, persistent upper lobar

pneumonia, atelectasis or air trapping.

TRACHEO-OESOPHAGEAL FISTULA• Associated with oesophageal atresia.• Polyhydramnious prenatally, postnatally the diagnosis

is usually made in the neonate, as they experience feeding difficulties and respiratory compromise due to repeated aspiration and failure to pass nasogastric tube.

• Around 50 % are associated with congenital anomalies: CVS anomallies, VATER/VACTERL, chromosomal anomalies, GI anomalies.

TRACHEO ESOPHAGEL FISTULA

Bronchial atresia• Focal obliteration of a proximal segmental or subsegmental bronchus

that lacks communication with the central airways. The development of distal structures is normal.

• The alveoli supplied by these bronchi are ventilated by collateral pathways through intraalveolar pores of the Kohn, bronchoalveolar channels of Lambert, interbronchiolar channels and show features of air-trapping, resulting in a region of hyperinflation around the dilated bronchi.

• Usually asymptomatic. May simulate a mass/ solitary pulmonary nodule or less frequently as congenital lobar emphysema.

• Chest Radiograph: Bronchocele, seen as rounded, branching opacities radiating from the hilum. The distal lung is emphysematous and produces an area of hyperlucency around the affected bronchi. In newborns, the affected segment may be seen as a fluid-filled mass.

• CT is an excellent modality for excluding the presence of a hilar mass and precisely determining delineation and location of lesions. In doubtful cases, multiplanar reformation helps distinguish mucoid impaction from nodular lesions.

BRONCHOPULMONARY FOREGUT MALFORMATIONS

1. Foregut abnormalities

Bronchogenic cyst

Esophageal/Neuroentericcyst

Tracheoesophageal fistula

2. Airway abnormalities

Tracheal Atresia

Bronchial Atresia

Tracheal Bronchus

3. Parenchymal abnormalities

Pulmonary Agenesis/Hypoplasia

CLE

Pulmonary sequestration

CPAM

Bronchogenic cyst• Represent around 50 % of the foregut malformations and are

the most common primary cysts of the mediastinum.• Bronchogenic cysts occur along the differentiating pathway of

the trachea and bronchial tree, and are thought to represent abnormal budding of foregut tissue.

•  They are lined by columnar ciliated epithelium, and their walls often contain cartilage and bronchial mucous glands. It is unusual for them to have a patent connection with the airway, but when present, such a communication may promote infection.

• Location: 1. Mediastinal : Most common.

Site: Para tracheal, carinal (M.C) , hilar.

2. Intrapulmonary: Medial third of the lung.

3. Lower neck ( V.Rare).

• Two-thirds of the patients are symptomatic; symptoms are due to the size and position of the cyst. Symptoms are most frequently caused by compression of the trachea or bronchi. However, most bronchogenic cysts in children are found incidentally when imaging is performed for other reasons.

• In infants and children, the chest radiograph is diagnostic for bronchogenic cysts in three out of four cases. The cysts are filled with serous or mucous fluid, so usually appear as water-density mass lesions in chest radiographs.

• CT: Locating an intrathoracic cyst, defining its extent, relation to key structures, and characterizing the intrinsic density. The cysts show no contrast enhancement, but when they become infected they may show wall enhancement.

• MRI: T1- Variable, T2- hyper intense.

Congenital cystic adenomatoid malformation• Also called as congenital pulmonary airway malformation.• Hamartomatous proliferation of the terminal bronchioles at the

expense of alveolar development between the 7th and 10th weeks of embryonic life, contain both cystic and solid tissue.

• Three types:

• TYPE 1: Most commmon ( 50 %)

Cysts of variable sizes with one dominant cyst( > 2 cm).

5 % aasocited with congenital anomalies.

Excellent prognosis.

TYPE 2: 41%

Small uniform cysts ( 1cm)

50 % associated with congenital anomalies.

• TYPE 3: Least common type.

Micro cysts and appears solid.

Usually involves one lobe.

Poor prognosis.

PULMONARY SEQUESTRATION• Pulmonary sequestration is defined as an aberrant lung tissue mass that has no normal connection with the bronchial tree or with the pulmonary arteries.

• The arterial blood supply arises from the systemic arteries, usually the thoracic or abdominal aorta.

CHARACTERSTIC

INTRALOBAR

EXTRALOBAR

Incidence More common ( 75 %)

Less common( 25 %)

Gender predisposition Equal Men 4: 1

Pleural investment Shares visceral pleura of parent lobe

Separate visceral pleura

Location Posterior basal segments(Approx. 60% on left)

Above, below or withindiaphragm(Approx. 90% on left)

Venous Drainage Pulmonary venous Systemic venous (azygos, IVC, portal)

Presentation Early adulthood with a history of pulmonary infection, chronic cough, or asthma.Asymptomatic mass (15%)

Mostly present during first 6 months of lifedue to respiratory orfeeding problems

RadiographicFeatures

Homogeneousconsolidation withirregular margins oruniformly dense masswith smooth or lobulatedcontours.

Single well defined,homogeneous, triangularshaped opacity in the lowerthorax. May presentelse where in the thoraciccavity.

SCIMITAR SYNDROME• Scimitar syndrome (SYN: pulmonary venolobar syndrome

or hypogenetic lung syndrome) is characterised by a hypoplastic lung that is drained by an anomalous vein into the systemic venous system.

• It is essentially a combination of pulmonary hypoplasia and PAPVR. It almost exclusively occurs on the right side.

• Haemodynamically, there is an acyanotic left to right shunt. The anomalous vein usually drains into IVC- M.C, right atrium, portal vein.

• The lung is frequently perfused by the aorta, but the bronchial tree is still connected and thus the lung is not sequestered.

• Associated anomalies: CHD, diaphragmatic anomalies, vertebral anomalies, GU anomalies.

• Three forms are described: Infantile, adult form, associated with anomalies.

PULMONARY UNDERDEVELOPMENT• 3 GROUPS : AGENESIS: Absent bronchi, lung.

APLASIA: Rudimentary bronchus without lung tissue.

HYPOPLASIA: Reduction in lung tissue.• The abnormality is usually unilateral, and there is no side or gender

predominance). More than 50% of children with pulmonary agenesis have associated congenital anomalies.

• HYPOPLASIA: It is characterized by the presence of both bronchi and alveoli in an underdeveloped lobe, and it is caused by factors directly or indirectly compromising the thoracic space available for lung growth, such as a congenital diaphragmatic hernia, extralobar sequestration, agenesis of the diaphragm, large pleural effusion, and Jeune syndrome (asphyxiating thoracic dystrophy), a rare entity in which a small and rigid thoracic cage produces a decrease in lung volume.

• The extrathoracic causes include oligohydramnios (Potter syndrome) . Other causes include decreased pulmonary vascular perfusion (tetralogy of Fallot, unilateral absence of the pulmonary artery).

CONGENITAL LOBAR OVERINFLATION ( ? EMPHYSEMA)• Characterized by progressive overdistention of a lobe, sometimes two lobes. It is thought to result from a ball-valve mechanism at the bronchial level.

• The most commonly affected lobe is the left upper lobe, followed by the middle lobe.

• In around 50 % of patients areas of malacia or stenosis of the bronchial cartilage were found and these are considered the most likely explanations.

• Myers described three clinical types. Infancy (type I), in older children (type II), or is an incidental finding in asymptomatic patients (type III). Types II and III are rare.

• Respiratory distress is the most common symptom at presentation.