Developmental disorders of lungsDr. Firoz A Hakkim

Chest Medicine

Introduction

Mostly congenital

Consequence of disordered organogenesis

May be diagnosed before birth or early in

postnatal life, so corrective surgery may be

applied

Period Stage Duration Charecteristics

Embryonic Embryonic 4-7 wks Start of

organogenesis,

formation of major

airway

Fetal Pseudoglandular 5-17 wk Formation of

bronchial tree &

large parts of

prospective

respiratory

parenchyma , birth

of acinus

Canalicular 16-26 wk Completion of

conducting airway ,

epithelial

differentiation. First

air blood barrier,

appearance of

surfactant

Sacular 24- term Expansion of

airway

Postnatal Alveolar 36 wks- preterm (1-

2 yrs)

Alveorazation

By formation of

secondary septa

(septation)

Microvascular

maturation

0-3 yrs Remodelling and

maturation of

interalveolar septa

and of capillary bed

Normal growth 2nd yr - adulthood Normal growth of

lung

Classification Tracheobronchial

anomalies

Anomalies involving

lung parenchyma

Anomalies of

pulmonary

vasculature

•Tracheal agenesis

•Tracheo – oesophageal

fistula

•Tracheal stenosis

•Tracheal narrowing due

to extrinsic pressure

•Tracheomalacia

•Tracheobronchomegaly

•Abnormal pattern of

bronchial branching

•Bronchial atresia

•Bronchogenic cyst

•Congenital

adenomatoid

malformation of lung

•Agenesis and

hypoplasia of lung

•Congenital

abnormalities of

lobulation

•Lung sequestration

•Absent pulmonary

artery trunk

•Absent unilateral

pulmonary artery

•Pulmonary artery

stenosis

•Anomalous orgin of

left pulmonary artery

•Anamalous systemic

pulmonary perfusion

•Anamalous pulmonary

venous drainage

(scimitar syndrome)

•Pulmonary

arteriovenous

malformation and

telangiectasia

Tracheobronchial anomalies

• Lower respiratory tract shares its embryological

origin with primitive foregut, arising from its ventral

surface in 4th wk of IUL as laryngotracheal bud or

respiratory primordial pouch

• Subsequent development of tracheobronchial tree

and oesophagus proceeds concurrently

• Congenital abnormality of one affects the other

• Developmental errors cannot arise after 16th wk of

IUL , since by this time its formation would have

been complete

Tracheal agenesis/ aplasia

• Absence of growth in trachea or in part of it

• Male: female :: 2:1

• 3 anatomical patterns

• Type 1- agenesis of proximal trachea. Distal trachea

is present, connected to oesophagus by fistulous

communication . 20 % cases

• Type 2 – main bronchi join in midline , communicate

with oesophagus by single fistula, 60% cases .most

common

• Type 3 – left and right main bronchi join oesophagus

20% cases

Tracheal agenesis/ aplasia

• Infant may survive for a period

• Early diagnosis may allow temporary

measures to sustain respiration , later

reconstructive surgery

Tracheo – oesophageal fistula

• H type tracheo –oesophageal fistula, both

trachea and oesophagus remain patent

• Maybe undetected until adult life

• Aspiration of oesophageal content into

airway may cause choking, with cough and

cyanotic episodes after feeding

• Passage of air through fistula into

oesophagus may cause abdominal distention

• Recurrent pneumonia is common

Tracheal stenosis

• Can be diffuse 30%, segmental 50%, or

funnel like 20%

• Associated with tracheo – oesophageal

fistulae, and accesory bronchi arising

from trachea

• Presents in infancy with stridor,

respiratory insufficiency

• Surgical treatment, plastic tracheal

reconstruction

Tracheal narrowing due to extrinsic

pressure

• Results from close proximity of unusually

large or abnormally placed vessels, that have

arisen as faulty devpt. of primitive system of

branchial arches

• Double aortic arch 47%, right aortic arch with

left ligamentum arteriosum 20%, retro

oesophageal right subclavian artery 14%,

anomalous innominate artery 11%,

anomalous left carotid artery 4%,

retrotracheal or sling left pulmonary artery

3%, right aortic arch with aberrant left

subclavian artery 1%

Double aortic arch

Sling left

pulmonary artery

Tracheomalacia

• Excessive weakness and collapsibility

of tracheal walls as a result of

abnormally soft or pliable cartilages

• Result of deficiency cartilge in a short

segment of trachea

• Result of prolonged ET intubation

• Rare systemic disorder like relapsing

poluchondritis

• Severe cases surgical intervention and

tracheal splinting procedures

Tracheobronchomegaly

• Charecterised by unusual widening of

trachea and main bronchi

• Inherited as an autosomal recessive

disorder in assoctn with EDS

• There is atrophic defect of the

connective tissue of trachea and main

bronchi

• Confirmed by ct

• c/f = wheezing dyspnoea, resp distress

during feeding, rec lrti, stridor, cyanosis

and apnoeic episode

Tracheobronchomegaly

Abnormal pattern of bronchial

branching

Most common anomaly is a

supernumerary rt upper lobe bronchus

May arise from trachea(0.9%) or rt main

bronchus(0.4%)

Most common segmental anomaly is a

double stem apical lower lobe

segmental bronchus (7%)- r >>lt

Supernumerary bronchus

• Bronchial isomerism – rare devpmt

anomaly in which normal pattern of

bronchial branching , in either rt or left

lung is mirrored in the contralateral lung

resulting in so called b/l rt or lt lung

Bronchial atresia

• Apicoposterior segment of lt upper lobe gets sealed from the

proximal airways to which it may remain attached by a thin

fibrous strand, so secretions get accumulated in the sealed

portion, which gets distended to form cystic space or mucocoel.

• Ventilation maintained by alveolar pores of kohn

• Pts majority asyptomatic.

Xray= mucocoel appears as a coin lesion and the part of lung

distal to it appears hypertransluscent ( air trapping)

Ct is confirmatory

Risk of infn is low

Surgical excision

Mucocoel, ( coin

lesion)

Bronchogenic cyst

• Result of abnormal budding of tracheo

bronchial tree during the course of

devpt. b/w 26 th day and 16 th wk of

IUL.

• So the tracheal and bronchial bud gets

separated from its parent, thereafter

developing into a cystic structure.

• M>>f

• Classified as central and periphery

• Central >peripheral

• Cysts may be single , multiple, or b/l lungs

• Ectopic site = pericardium, diaphragm, vertebral

column

• Infected cyst may have fluid level

• c/f = presure effect on trachea cause dyspnoea ,

cough and stridor, on oesophagus dysphagia

• Repeated resp. Tract infection

• Complication – haemoptysis, pneumothorax

• Xray and ct diagnostic

• Xray = well circumscribed , rounded

homogenous opacity , close to major

airway or in the periphery

• Surgical excision of the cyst

Bronchogenic cyst