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CONGENITAL ANOMALIES OF AIRWAY AND LUNG PARENCHYMA

DR.GOPAL CHAWLAJUNIOR RESIDENT,

DEPT OF PULMONARY MEDICINE, GMC, PATIALA

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SEMINAR OUTLINE•INTRODUCTION

•EMBRYOLOGY OF LUNG DEVELOPMENT

•CLASSIFICATION

•INDIVIDUAL AMOMALIES

•CONCLUSION

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INTRODUCTION•Developmental anomalies of lung are usually detected in neonatal period and early childhood

•Some are not encountered until late childhood and adulthood

•Some can be confused with more sinister abnormalities

•While some can often be missed

•An understanding of imaging features and the clinical presentation is important for any respiratory physician

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Embryologic Development of the Lungs•The intrauterine development of the human lung has been divided into five phases: embryonic, pseudoglandular, canalicular, saccular, and alveolar

•During the fourth week (26th day) of gestation the Respiratory diverticulum (lung bud)appears as an outgrowth from the ventral wall of the foregut .

•Next 2days right and left bud arise from outpouching.

•Respiratory portion of gut becomes separated from esophageal by tracheoesophageal septum

•Lung buds elongate into primary lung sac and the 5 lobar bronchi appear upto 5th week this is Embryonic phase

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Pseudoglandular stage•week 5 - 17•tubular branching of the human lung airways continues•by 2 months all segmental bronchi are present.•lungs have appearance of a gland like structure.•stage is critical for the formation of all conducting airways.•lined with tall columnar epithelium, the more distal structures are lined with cuboidal epithelium.

Canalicular stage•week 16 - 24•Lung morphology changes dramatically•differentiation of the pulmonary epithelium results in the formation of the future air-blood tissue barrier.•Surfactant synthesis and the canalization of the lung parenchyma by capillaries begin.

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Saccular stage•week 24 to near term.•most peripheral airways form widened airspaces, termed saccules.•saccules widen and lengthen the airspace (by the addition of new generations).•future gas exchange region expands significantly.•The vascular tree also grows in length and diameter during this time.

Alveolar StageIn the alveolar phase after birth more and more alveoli form from the terminal endings of the alveolar sacculi and with time increase in diameter. They are delimited by secondary septa.

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ANOMALIES OF AIRWAY

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Anomalies of higher airwayChoanal Atresia

Choanal atresia is a congenital narrowing of the back of the nasal cavity that causes difficulty breathing. It is rare, occurring in 1 in 7000 live births, Seen more often in females than in males. It can be bilateral, or unilateral

Bilateral choanal atresia often have respiratory distress episodes immediately after birth. These are relieved only when the patient begins to cry. The child can not breathe during normal circumstances and can only breath when they open their airway to cry

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Glottic stenosis is a narrowing of the larynx where the vocal cords are scarred together. Posterior glottic stenosis (narrowing in the back of the vocal fold area) may occur in conjunction with subglottic stenosis. In 90 percent of cases, glottic stenosis is the result of prolonged endotracheal intubation. Ten percent of cases are congenital, or present at birth.

Glottic stenosis

Laryngeal AtresiaLaryngeal atresia is a complete upper airway obstruction that occurs when the larynx fails to open during a baby's development in utero and remains blocked by cartilage or other tissue .The infant will require an immediate tracheostomy at birth in order to survive. This condition is also called CHAOS (Complete High Airway Obstruction Syndrome).

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Laryngomalacia•Laryngomalacia is a congenital softening of the tissues of the larynx above the vocal cords. •This is the most common cause of noisy breathing in infancy. •The laryngeal structure is malformed and floppy, causing the tissues to fall over the airway opening and partially block it.•will resolve without surgery by the time they are 18 to 20 months old

Laryngotracheal Cleft (LTC)•Laryngotracheal cleft (LTC) is a rare congenital defect in which there is a gap between the upper airway passage (larynx and possibly trachea) and the food passage (esophagus)•septum does not completely develop, resulting in variable degrees of communication between the airway and esophagus. Because of the defect the child can inadvertently aspirate food or even secretions into the lungs

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Tracheal Agenesis and Atresia. •The trachea may be completely absent (agenesis), or it may be partially in place but considerably underformed (atresia). They are uniformly fatal and are fortunately quite rare

•Since first reported by Payne in 1900, less than 100 cases have been reported to date.

•According to Merei et al , the point of bifurcation between the developing trachea and developing esophagus at foregut remains fixed in relation to the cervical vertebra. Caudally, the respiratory diverticulum will develop into the carina and broncho-pulmonary tree. The cephalic aspect of the respiratory diverticulum will be elongated to form the trachea and the infra-glottic structure. Tracheal agenesis results when this normal elongation process fails to take place.

•Communication between the larynx proximally and the alveoli of the lungs distally is lacking. Because of the lack of a normal continuous airway, affected newborns survive only if an alternate pathway for ventilation (eg, a patent bronchoesophageal fistula) exists.

Merei JM, Hutson JM: Embryogenesis of tracheoesophageal anomalies: a review.Pediatr Surg Int 2002, 18:319-326.

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Tracheal agenesis should be suspected in a newborn baby who presents with immediate respiratory distress, as well as extremely weak cry and failed intubation despite adequate ventilation with facemask.

In all three types a tracheoesophageal fistula exists (arrowhead). Type I, a short segment of distal trachea arises from the anterior wall of the esophagus before dividing into the mainstem bronchi. Type II, there is complete agenesis of the trachea, with a fistula between the esophagus and carina from which the two mainstem bronchi originate(commonest). Type III, the two mainstem bronchi arise individually from the anterior esophageal wall.

Floyd’s classification of tracheal agenesis

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•Congenital tracheal stenosis is a rare disorder characterized by the presence of focal or diffuse complete tracheal cartilage rings, resulting in a fixed tracheal narrowing.

•A variety of stenosis patterns have been described, Approximately 50% of congenital tracheal stenoses are focal, 30% generalized, and 20% funnel-shaped

•The entity may be seen in isolation or in conjunction with other anomalies, the most common of which is the pulmonary artery sling complex . It is a rare congenital anomaly in which the left pulmonary artery originates from the right pulmonary artery and encircles the right mainstem bronchus and distal trachea, causing compression of each.

•Focal congenital tracheal stenosis consists of a simple local narrowing of the trachea, usually in the lower third. The distal end of the trachea and bronchi are of normal size•90% present during the 1st year of life, often with biphasic stridor.

• Infants diagnosed early in life - worse prognosis.

• Degree of stenosis more critical than length.

Tracheal stenosis

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Diagnosis - Frontal and lateral high-kilovoltagefiltered radiographs combined with barium esophagography.CT only in selected cases.

Helical CT or Electron Beam- CT - useful for evaluating dynamic changes in the airway.

Symptoms include:1. Noisy breathing (stridor)2. Recurring pneumonia3. Wheezing4. Cyanosis (blue-spells)5. Apnea (breathing pauses)6. Chest congestion

Microlaryngoscopy and bronchoscopy help differentiate between tracheal lesions and other lesions in the larynx that can cause stridor and respiratory distress, and can help show the degree and length of narrowing in the trachea.

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Observation.Milder forms of tracheal stenosis which do not significantly affect the patient may be monitored with close observation . As the child and the airway grows, the condition may improve over time.

Treatment for tracheal stenosis

NON SURGICALBalloon dilation. • In less severe cases of tracheal stenosis,

scar tissue may be divided with a sickle knife and then dilated with an angioplasty-like balloon during an endoscopic, non surgical procedure. The formation of new scarring can be avoided by injecting the tissue with a steroid or mitomycin during the time of balloon dilation. 

Airway stents – Small tubes are placed in the airways to hold the airways open.

Argon plasma coagulation (ACP) – Argon is used to apply heat to the scar

• or tumor tissue to open the narrowing o that they overlap, providing a wider tracheal airway.

SURGICALTracheal resection and primary anastamosis.More severe cases may require open surgical intervention with reconstruction. For severe narrowing involving a few tracheal rings, tracheal resection and anastomosis may be performed. This involves surgically removing the defective tracheal segment and then repairing the airway by suturing the remaining ends back together..

Slide tracheoplasty. In long-segment tracheal stenosis, a slide tracheoplasty is required. In this surgery, the narrow part of the trachea is cut horizontally. Then a vertical incision is made in the back part of one segment and the front part of the other tracheal segment. Finally, the two sections are slid together and sutured

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Tracheomalacia

Tracheomalacia can be classified as primary and secondary.

Primary tracheomalacia occurs as a primary lesion due to abnormal development of tracheal cartilage. If the lesion involves the extrathoracic portion of trachea then obstruction occurs during inspiration, and if it is intrathoracic then the obstruction occurs during expiration. Since majority of trachea lies intrathoracic obstruction occurs during expiration.

Secondary tracheomalacia occurs always in conjunction with conditions that compress the airway. It could be mediastinal mass, vascular arches and malformations compressing trachea. Rarely thryoid malignancies may cause secondary tracheomalacia. In children chronic aspiration can cause secondary tracheomalacia.

Tracheomalacia is defined as tracheal wall softening due to an abnormality of the cartilaginous ring and hypotonia of the myoelastic elements. Tracheomalacia exists when the cartilaginous framework of the trachea is unable to maintain airway patency.

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Age of occurence: Since tracheomalacia commonly encountered is of primary variety, it is seen in infants and young children. In majority of cases the tracheal lumen increases in size, and the tracheal cartilages firm up causing resolution of symptoms by the time child reaches the age of 3

Complaints: The patient has wheeze which manifests in affected child between 4-8 weeks. These children are also known as "Happy Wheezers" because despite their airway problems they maintain good oxygen saturation and grow normally which is in contrast to patients suffering from cystic fibrosis or bronchial asthma.

Physical findings:1. The baby appears to be clinically well despite the wheeze2. Patients respiratory rate and oxygen saturation are mostly normal except in extreme cases when the respiratory rate may increase.3. Feeding difficulties have also been reported4. Inspiratory retraction of supraclavicular and intercostal spaces occur5. Thoracic deformity is also seen in some patient with tracheomalacia

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Investigations:X-ray chest may reveal hyperinflation and tracheal lumen narrowing during expiration. Vascular anomalies like double aortic arch may also be revealed in the chest radiograph.Dynamic expiratory CT scans may be useful in clinching the diagnosisCineflouroscopy with contrast in the oesophagus may also demonstrate tracheomalacia

Bronchoscopy: Is diagnostic. The cardinal features seen in bronchoscopy are:1. Loss of normal semicircular shape of tracheal lumen2. Forward ballooning of posterior tracheal wall3. Antero posterior narrowing of tracheal lumen

Management:•Primary tracheomalacia of milder variety can be managed by conservative means. Most of the infants manage to out grow this problem by the time they reach 3 years.If the patient has retained secretions, chest physiotherapy may be of help.•Reflux oesophagitis if present should be treated aggressively. •Systemic steroids may be of some help in some patients with associated tracheitis.•Continuous postitive pressure ventilation may be adminsitered via nasal mask to tide over acute crisis.If tracheomalacia involves proximal segment of trachea then tracheostomy or stenting can be resorted to in extreme cases.

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a) Axial CT image in the neutral position (quiet inspiration) revealed flattening of the distal trachea with increased coronal diameter relative to sagittal diameter (yellow arrow). By dynamic CT; (b) Axial CT image at the end of forced inspiration revealed complete inflation of the trachea (c) Axial CT image at the end of forced expiration revealed complete flattening mounting to near total collapse of the trachea with lunate configuration of the trachea which is characteristic for tracheomalacia (black arrows). (d) CT bronchography image revealed the previously mentioned flattening of the distal trachea as labeled in the image.

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Tracheal Bronchus(Pig Bronchus or bronchus suis)

•Tracheal bronchus was described by Sandifort in 1785 as a right upper bronchus originating in the trachea.•PIG Bronchus is said when entire upper lobe is aerated by this bronchus.•The rate of incidence is estimated to range around ~ 0.1 - 2% and there is a marked right sided predilection•Tracheal bronchus includes a variety of bronchial anomalies arising in the trachea or main bronchus and directed toward the upper-lobe territory. This anomalous bronchus usually exits the right lateral wall of the trachea less than 2 cm above the major carina and can supply the entire upper lobe or its apical segment

Displaced Tracheal Bronchus Superanummery Tracheal Bronchus

If the anatomic upper-lobe bronchus is missing a single branch, the tracheal bronchus is defined as displaced

if the right upper-lobe bronchus has a normal trifurcation into apical, posterior, and anterior segmental bronchi, the tracheal bronchus is defined as supernumerary

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The supernumerary bronchi may end blindly; in that case, they are called tracheal diverticula. If they end in aerated or bronchiectatic lung tissue, they are termed apical accessory lungs or tracheal lobes

Patients are usually asymptomatic, but the diagnosis of tracheal bronchus should be considered in cases of

persistent or recurrent upper-lobe pneumonia, atelectasis or air trapping, and chronic bronchitis.

Shih FC, Lee WJ, Lin HJ. Tracheal bronchus. CMAJ. 2009;180 (7): 783.

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Gower WA, Mcgrath-morrow SA, Macdonald KD et-al. Tracheal bronchus in a 6-month-old infant identified by CT with three-dimensional airway reconstruction. Thorax. 2008;63

CT is Best for assessing anatomy. Allows direct visualisation and orientatation of anomalous bronchus. Coronal multi-planar reconstructions in "lung window" settings are the most helpful and is best in depicting this anomaly.

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Tracheo-esophageal Fistula (TOF)

Esophagus and tracheal originate from the median ventral diverticulum of the forgut, separated by esophagotracheal septumTOF: esophageal and tracheal failure to separate during divison of the endoderm

Esophageal atresia in the fetus should be considered as a cause ofMaternal polyhydramnios. Absence of stomach gas Develop copious, fine white frothy bubbles of mucus in the mouth and nose. Secretions recur despite suctioning.

•Infants may develop rattling respiration and episodes of coughing and choking in association with cyanosis.•Symptoms worsen during feeding

SUSPECTED WHEN

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Clinical Symptoms of Child with TOF• Drooling, regurgitation, Coughing &Choking on feeding• Scaphoid abdomen = EA• Distented abdomen = TEF• Cyanotic episodes• Inability to pass OGT• Pneumonia , atelectasis (abdomen P)

Prenatal diagnosis of congenital TEFs: Prenatal ultrasound may reveal •polyhydramnios, •absence of fluid-filled stomach, •small abdomen, •lower-than-expected fetal weight, •distended esophageal pouch.

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Postnatal diagnosis of congenital TEFs

Plain chest radiographs may reveal tracheal compression and deviation. Absence of a gastric bubble indicates esophageal atresia without a TEF or esophageal atresia with a proximal TEF. Chest radiography leads to the diagnosis of TEF in most cases of congenital TEF

Aspiration pneumonia in the posterior segments of the upper lobes may occur secondary to aspiration of the contents from the esophageal pouch or stomach. Recurrent or massive aspiration may lead to acute lung injury in some patients.

Insertion of a nasogastric tube may show coiling in the mediastinum of patients who have concomitant esophageal atresia. This finding is diagnostic of TEFs associated with esophageal atresia.

Multidetector- row CT - Presence of TEF was correctly diagnosed with multidetector-row CT esophagography. Furthermore, the images provided crucial information for planning surgery, and, without contrast medium, it is a less invasive examination.

Bronchoscopy• Level of fistula• Exclude upper pouch fistula• Identify laryngoesophageal cleft

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Type a is EA without a TEF and is often called pure EA. Type b has a connection (fistula) between the upper pouch and the trachea (a TEF). Type c is by far the most common form of EA and has a fistula between the lower esophagus and the trachea (one form of TEF) with a blind upper pouch. Type d with two TEFs, one between both the upper and lower esophageal segments and the trachea. Type e has only a TEF and no EA. This is usually referred to as an H or N shaped fistula and may be 2-4% of this group. The H-fistulas are divided surgically and nothing further needs to be done to the esophagus which is intact and reaches normally to the stomach

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ManagementMedical

• NPO• Avoid bag-mask ventilation• 45° head up• Low continuous suctionin of

esophageal pouch• Pediatric centre transfer• IVF, Abx• VitK, TPN as needed• ECMO

Surgical• One stage repair: optimal surgical

management– Fistula is ligated, proximal and distal

ends of the esophagus are anastomosed

• Gastrostomy:– High risk infants unable to withstand a

thoracotomy– Decompress the stomach and prevent

regurgitation via fistula into the lungs

• Definitive repair– 24-72 hours later, when infant can

withstand both surgery and anesthesia

– Method: right thoracotomy using a posterolateral extrapleural approach

– Fistula is ligated, esophageal segments are anastomosed

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Bronchial Atresia•Congenital bronchial atresia is a rare anomaly that results from focal obliteration of a proximal segmental or subsegmental bronchus that lacks communication with the central airways while development of distal structures is normal

•The apicoposterior segmental bronchus of the left upper lobe is most often involved, followed by segmental bronchi of the right upper, middle, and lower lobes

•Most often affects segmental bronchi at or near their origin.

•Bronchi distal to the stenosis become filled with mucus → bronchocele.

•Distal hyper-inflation is believed to be caused by collateral ventilation through intraalveolar pores of Kohn, bronchoalveolar channels of Lambert, and interbronchiolar channels The alveoli supplied by these bronchi show features of air-trapping, resulting in a region of hyperinflation around the dilated bronchi

•The abnormality is an incidental finding in approximately 50% of cases, mostly in young men, and generally produces no symptoms or signs.

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Characteristic chest radiographic findingBronchocele → A classic radiographic finding of bronchial atresia is a branching tubular or nodular area of increased opacity that extends from the hilum with surrounding hyperlucent lung parenchyma. Images acquired during both inspiration and expiration may help confirm that a lung is hyperinflated.

CT- Sensitive modality for demonstrating the typical features → mucoid impaction , segmental overinflation and hypovascularity

The differential diagnosis includes other abnormalities with mucus impaction, such as allergic bronchopulmonary aspergillosis, cystic fibrosis, or any lesion that causes bronchial narrowing and thus mucus impaction. The presence of a mucocele with adjacent hyperinflation helps narrow the differential diagnosis.

Oh KS, Dorst JP, White JJ. The syndrome of bronchial atresia or stenosis with mucocele and focal hyperinflation of the lung. Johns Hopkins Med J1976; 138:48-53.

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Bronchial atresia

(a) CT scan shows air trapping in the right upper lobe (arrows). (b) CT scan in the same patient shows a round opacity at the site of

the atresia, medial to the air trapping, representing mucoid impaction just distal to the atresia.

CT is an excellent modality for excluding the presence of a hilar mass and precisely determining delineation and location of lesions.

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Bronchogenic CystBronchogenic cysts form as a result of abnormal budding of the bronchial tree during embryogenesis (between 4th - 6th weeks), and as such they are lined by secretory respiratory epithelium (cuboid or columnar ciliated epithelium) . The wall is made up of tissues similar to that of the normal bronchial tree, including cartilage, elastic tissues, mucous glands and smooth muscle Bronchogenic cysts are rare congenital lesions accounting for only 5 - 10% of paediatric mediastinal masses . The incidence of mediastinal cysts is equal between the sexes whereas intrapulmonary cysts are reported to have a male predilection

Bronchogenic Cyst are usually solitary , thin walled unilocular , and roughly spherical in shape and are filled with either mucoid or serous fluid and do not communicate with tracheobronchial tree unless they become infected , in that case cyst fluid may be replaced by pus or airfluid level

Aspiration of cyst yielding mucus and bronchial epithelial cell confirm the diagnosis

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The most common location is the middle mediastinum (65 - 90%). The distribution of locations can be quite varied :

Mediastinal : ~ 70% usually does not communicate with the tracheo-bronchial treesub-carinal, right paratracheal and hilar locations most common approximate incidence includes

carinal area : ~ 50%para-tracheal area : ~ 20%orophageal wall : ~ 15%retrocardiac area : ~ 10%

Parenchymal (intrapulmonary)typically perihilarpredilection for lower lobes

Other uncommon locationsneckcutaneous pericardium extending across the diaphragm and appearing dumb-bell shaped retroperitoneal

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Pulmonary Bronchogenic Cyst

• If uninfected No symptoms• Most common symptom

Hemoptysis if infected• Sharply circumscribed , round or

oval nodule or mass , usually in medial third of lung

• Prediliction of lower lobe• Lesion don’t communicate with

tracheobronchial tree• Sometimes get calcified• If communicate , it may incorporate

check valve mech causing rapid expansion of it

• On CT smooth thin wall with non enhancing homogenous attenuation at near water density (0-20HU)

• On MRI signal intensity on T1 weighted images is intermediate between that of muscle and subcutaneous fat

Mediastinal Bronchogenic Cyst

• 5 types• Symptoms because of pressure ,

dyspnoea on exertion stridor , persitent cough and chest pain

• Paratracheal and carinal most common• Majority oval and round • Cleary defined mass of homogenous

density in Right paratracheal region or just inferior to and slightly to the right of carina

• In contrast to pulmonary rarely communicates w ith tracheobronc tree

• Calcification is uncommon• Almost 50 % have higher attenuation CT

130 U making it indistinguishable from soft tissue because of higher level of protein content

• On MRI variable intensity on T1 weighted imaged while consistently high intensity signal on T2 images

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Pulmonary Bronchogenic Cyst Mediastinal Bronchogenic Cyst

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Complications •Fistula formation with the bronchial tree•Ulceration of the cyst wall•Secondary bronchial atresia •Superimposed infection•Haemorrhage•Malignant transformation is very rare, but reported, with primaries including :

rhabdomyosarcomapleuropulmonary blastomaanaplastic carcinomaleiomyosarcomaadenocarcinoma

Treatment and prognosisThe choice of treatment is somewhat controversial. Some advocate surgical excision of all cysts given their tendency to become infected or rarely, to undergo malignant transformation . Increasingly, these lesions are treated with transbronchial or percutaneous aspiration under CT guidance to both confirm the diagnosis and to treat them. Small lesions can be followed, however they do have a tendency to increase in size over time, sometimes rapidly

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Accessory Cardiac Bronchus

•A cardiac bronchus is a rare variant of normal bronchial anatomy , arising from the inner wall of the right main bronchus or intermediate bronchus opposite to the origin of the right upper lobe bronchus

•Its rare and is reported in around 0.09 to 0.5% of individuals . Males predilection

• It is the only recognised true supernumerary bronchus. It is variable is size, morphology and length (range from 5mm to 5cm)

•The vast majority of cardiac bronchi are asymptomatic. In some patients with lung parenchyma supplied by this bronchus, abnormal drainage predisposes to repeated chest infection . Haemoptysis has also been described

•. In about half of cases the cardiac bronchus is a short blind ending bronchial stump with no branches and does not supply any lung parenchyma. In the remainder, the bronchus may have branches and a an amount of aerated lung parenchyma

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endoscopic view shows accessory cardiac bronchus separated by a spur from the middle part of the intermediate bronchus.

show an accessory cardiac bronchus (arrowhead) that originates from the medial aspect of the right main bronchus

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•The accessory cardiac bronchus has a round orifice and is directed caudally, toward the pericardium

• It is lined by normal bronchial mucosa and has cartilage within its walls, which distinguishes it from an acquired fistula or diverticulum

•Most patients with an accessory cardiac bronchus are asymptomatic. Symptomatic patients may present with recurrent infections or hemoptysis

•A cardiac bronchus is almost always an incidental finding of CT examination of the chest. It appears as a continuation of the the lumen of the right main bronchus, projecting medially and directly inferiorly towards the posterior aspect of the heart.

In some cases the dependent lung parenchyma may be collapsed and mimic a soft tissue mass

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Abnormal patterns of bronchial branching•Incidental finding during bronchoscopy .

•Of importance during resective surgeries

•The abnormalities are more often additive than subtractive

•The most common major anomaly is a supernumerary right upper lobe bronchus ,which may arise anywhere from the trachea or right main bronchus

•Absence of an upper lobe bronchus is the most common of the major subtractiveabnormalities (0.3%).

•The most common segmental anomaly is a double-stem apical lower lobe segmentalbronchus that occurred in 7% , the incidence being slightly higher on the right than on the left

•Bronchial isomerism is a term applied to a rare group of developmentally anomalous syndromes in which the normal pattern of bronchial branching in either the left or the right lung is mirrored in the contralateral lung, resulting in a so-called bilateral left or right lung

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Anomalies of the Lung

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Pulmonary UnderdevelopmentPulmonary underdevelopment has been classified into three groups by Schneider and Schwalbe

Group 1, Agenesis : bronchus and lung are absent Group 2, Aplasia: a rudimentary bronchus is present and limited to a blind-end pouch without lung tissue

Group 3, Hypoplasia : there is bronchial hypoplasia with variable reduction of lung tissue

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Lung Agenesis

•The abnormality is usually unilateral, and there is no side or gender predominance

•Most of the limb and spinal anomalies are ipsilateral to the pulmonary agenesis, whereas the rib anomalies are variable. The contralateral lung is normal in structure but has compensatory hypertrophy.

•Patients with right-lung agenesis have a shorter life expentancy than those with left-lung agenesis; this suggests that the right-lung agenesis has a greater frequency of an associated shift of the heart and mediastinum, with corresponding distortion of bloods vessel and bronchi

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The diagnosis of lung agenesis is usually first suspected at chest radiography that demonstrates a small, completely opaque hemithorax with displacement of the mediastinal structures and diaphragm

Ocasionally, the agenesis may be confined to one lobe, most frequently the left upper lobe

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Bronchography verifies that the mainstem bronchus is completely missing, and angiography demonstrates the absence of pulmonary and bronchial arteries on the side of the absent lung .

Conventional CT, MR imaging, and angiography may provide important diagnostic information, showing the absence of lung parenchyma, bronchial tree, and pulmonary vessels on the affected side .

CT angiography and MR angiography are currently the imaging modalities of choice in the diagnosis of this entity, with angiography used only in selective cases.

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Pulmonary Hypoplasia•is defined as deficient or incomplete development of the lungs . •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

Extrathoracic Causes Intrathoracic Causes

1. Oligohydramnios2. Potter syndrome 3. Decreased pulmonary

vascular perfusion (tetralogy of Fallot, unilateral absence of the pulmonary artery)

1. Congenital diaphragmatic hernia, are the most common

2. Extralobar sequestration, agenesis of the diaphragm

3. Large pleural effusion4. Jeune syndrome

(asphyxiating thoracic dystrophy), a rare entity in which a small and rigid thoracic cage produces a decrease in lung volume.

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Most common manifestation is early respiratory distress after birth, cyanosis, tachypnea, hypoxia, hypercapnea, and acidosis.

Pneumothorax and pulmonary hypertension are common serious complications

Anteroposterior chest radiograph of a 7-month-old infant shows opacity of the left hemithorax and pulmonary hypoplasia with ipsilateral displacement of the mediastinum, secondary to repaired Bochdaleck hernia.

MR imaging may provide additional valuable information. Normal pulmonary tissue has homogeneously high signal intensity. In fetuses with lung hypoplasia, a decrease in signal intensity has been reported

Çay A, Sarihan H. Congenital malformation of the lung. J Cardiovasc Surg2000; 41:507-510.

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Congenital Cystic Adenomatoid Malformation CCAM /CPAM

•Congenital cystic adenomatoid malformation is a rare abnormality of lung development. •CCAM is a cystic area within the lung that stems from abnormal embryogenesis.•First described by Ch'in and Tang in 1949 •Recently termed Congenital Pulmonary Airway Malformation CPAM• An adenomatous overgrowth of the terminal bronchioles with a consequent reduction in alveolar growth occurs.•Characterized by architecturally abnormal pulmonary tissue with or without gross cyst formation, with vascular supply is more often by pulmonary circulation .•Pathogenetically, congenital cystic adenomatoid malformation has been attributed to an overgrowth of bronchioles, with almost complete suppression of alveolar development between the 7th and 10th weeks of embryonic life •Cases are typically identified prenatally by routine ultrasonography screening. Most postnatally identified cases present in the newborn period.

•CCAM may present in the older child and adult as an incidental finding or secondary to repeated infection

Prenatal Ultrasound Classification of Adzick (macrocystic = >5 mm; microcystic = <5 mm)

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Stocker’s Classification 1971,2001Type Salient features

Type | •Most common 59 %•Large multi loculated cysts , 1 or more cyst more than 2cm•Cyst wall lined by smooth muscle but no cartilage•Lined by bronchiolar type epithelium•Foci of mucus secreting epithelium seen in adjacent lung tissue , in lepidic pattern identical to bronchioalv ca

Type || 38 % Intermediate formSolid areas separated by fairly even spaced cysts measuring1 to 10 mmLined by ciliated columnar or cuboidal epithelium

Type ||| 9%Solid formBulky solid mass of tissue without gross cyst formationMicroscopically abnormal tissue composed primarily of irregularly shaped bronchiolar and alveolar structure resembling PSEUDOGLANDULAR period of fetal development

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In 2001, Stocker expanded that classification, adding type 0 lesions (previously reported as acinar dysplasia of the lung) and type 4 lesions (a type of peripheral lung cyst manifesting with pneumothorax). The lesions were renamed types 0–4 CPAM because neither cystic or adenomatoid features are always present.

Type 0 CPAM is the least common type of CPAM and accounts for less than 3% of all cases. Also known as acinar dysplasia or agenesismay involve any of the pulmonary lobes, has either no cysts or very small ones (<0.5 cm), and is incompatible with life . It represents severe global arrest of lung development.

Type 4 CPAM consists of large cysts up to 10 cm in diameter and accounts for 10%–15% of cases of CPAM . It is not readily distinguishable either clinically or radiologically from type 1 CCAM/CPAM; however, it has a unique association with tension pneumothorax

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1.Respiratory distress is the presenting symptom in most newborns . It may range in severity from grunting, tachypnea, and a mild oxygen requirement to fulminant respiratory failure requiring aggressive ventilator support or extracorporeal membrane oxygenation (ECMO).Pulmonary hypoplasia may arise as a consequence of a large CCAM, mediastinal shift may compromise cardiac and respiratory function, spontaneous pneumothoraces may occur, and air trapping within the cyst leads to compression of functional pulmonary tissue.

2.Recurrent infection: risk of recurrent pulmonary infections due to bronchial compression, air trapping, and inability to clear secretions.

3.Hemoptysis: Hemoptysis has occasionally been described as a manifestation of CCAM in the older child.

4.Dyspnea and chest pain: Dyspnea may be a feature of pneumothorax, which has been described as a presenting feature of CCAM.

5.Miscellaneous: Cough, fever, and failure to thrive have all been reported in association with the presentation of CCAM.

Physical Signs and Symptoms

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Type I CCAM(a)AP chest radiograph of a 5-year-old shows a bubbly mass in the left upper lobe with a dominant air cyst more than 4 cm in diameter (arrows). (b) CT scan of the same patient shows a hypoattenuating, clearly delineated cystic mass

Type II CCAM. a)X rayof a newborn shows a heterogeneous bubbly mass in the left lung displacing mediastinal structures to the right. (b) Coronal T1-weighted image in the same patient shows cysts (arrows) smaller than 2 cm in diameter.

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Management

•Symptomatic infants with CCAM/CPAM should undergo urgent surgical excision—generally lobectomy, since segmental resection may result in incomplete resection or persistent pneumothorax.

•The management of asymptomatic cases is controversial, and most pediatric surgeons advocate elective resection . Although some antenatally diagnosed lesions (4%–15%) may regress postnatally within the first year , persistent unresected lesions carry a risk of recurrent lung infections and a small risk of the subsequent development of a malignant neoplasm

•Priest et al suggest that surgery be delayed until a child is 9 months old to allow possible spontaneous resolution of CCAM/CPAM without putting the patient at risk for malignant transformation.

Chuang S, Sugo E, Jaffe A ,A review of postnatal management of congenital pulmonary airway malformations. Fetal Matern Med Rev 2009;20(3):179–204.

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Pulmonary sequestrationPulmonary 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, and its venous drainage is via the azygous system, the pulmonary veins, or the inferior vena cava

Sequestration is divided into two types: extralobar and intralobar

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Extralobar• Entirely separate segment of lung tissue

invested in its own pleural layers (25% of PS).

• Typically found in the costophrenic sulcus on the left side. (90 % left sided).

• May also be located in the mediastinum, pericardium, and within or below the diaphragm.

• Arterial supply :Abdominal/ thoracic aorta (85-90%) CeliacAxis,subclavian arteries, intercostal arteries(10%–15%)

• Venous Drainage :Systemic Circulation (Azygous System/IVC) 80%Pulmonary Circulation 20 %

• diagnosed early (4:1 Male predominance)• Associated with other congenital

malformations (~50%)

Intralobar• Shares the visceral pleural

covering of the normal adjacent lung tissue(75% of PS).

• Usually located in the posterobasal portion of the lower lobes.

• Arterial Supply :Thoracic/ upper abdominal aorta

• Venous Drainage:Pulmonary venous system.

• usually diagnosed in childhood

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Prenatal Diagnosis

1. USG: Hyperechoic mass, usually in the posterior basal hemithoraxSometimes it is associated with a small cyst. Extralobar sequestration may be seen as an infradiaphragmatic mass.

2. Color Doppler ultrasonography is useful for demostrating anomalous vessels and tracing them to their origin

3. Prenatal MR imaging shows a well-defined mass with sharp margins and high signal intensity

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Postnatal Diagnosis1. Chest X Ray, it has the appearance of a soft-tissue

opacity in the posterior basal segment of the lung, with smooth or lobulated margins,.

Brochiectasis, subsegmental atelectasis, mediastinal shift, and prominence of the ipsilateral hilum are additional radiographic findings

2. CT Chest , CT scans show a soft-tissue cystic mass containing air or fluid, focal emphysema, and a hypervascular focus of lung tissue

3. MR imaging and angiographic MR imaging are better for differentiating the cystic, solid, hemorrhagic, and mucous components of the mass than is CT. They also demonstrate the systemic vascular supply of the sequestration

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Coronal postnatal CT scan shows a homogeneous mass in the posterior segment of the left lower lobe. A feeding artery (arrow) is seen arising from the aorta, a finding that is diagnostic for sequestration.

Intraoperative photograph obtained patient with sequestration shows variable-sized ectopic masses inferior to the lung, the larger of which (*) is seen with a vascular supply (arrow) from the descending aorta.

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Congenital Lobar Emphysema(NEONATAL LOBAR HYPERINFLATION)

•Congenital lobar emphysema is characterized by progressive overdistention of a lobe, sometimes two lobes.

•Result from a check-valve mechanism at the bronchial level that causes progressive hyperinflation of the lung by allowing more air to enter the involved area on inspiration than leaves on expiration

•There is no destruction of alveolar walls and is not truly congenital

•So, this is misnomer and has been replaced with term NEONATAL LOBAR HYPERINFLATION

•The most commonly affected lobe is the 42.2% in the left upper lobe, 35.3% in the right middle lobe, 20.7% in the right upper lobe, 0.9% in each lower lobe

•It is more common among males than females; it is not familial and occurs predominantly in Caucasians.

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•Most patients become symptomatic during the neonatal period, most before 6 months of age

•Myers Classification :•Symptomatic in infancy (type I), older children (type II), or incidental finding in asymptomatic patients (type III).

•Etiology– Not found in up to 50%– Bronchial obstruction found in ~25%Allows collapse on exhalation (ball-valve mechanism)Air trapping leads to alveolar overinflation

Intrinsic obstruction (more common) – Intramural: Defect in the bronchial wall Defective quantity or quality of cartilage – Intraluminal: Lesion in the lumen of the bronchus Redundant bronchial folds, mucous plugs

Extrinsic obstruction – Compression of the bronchus from a lesion outside the bronchial wall Cardiovascular: PDA, vascular sling Mass: Lymph node, bronchogenic cyst, oncologic mass

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Presentation– Age• At birth: 33%• By 1 m.o.: 50%• After 6 m.o.: 5%

– Symptoms (in order of decreasing frequency)• Moderate respiratory distress (most)• Cyanosis (half)• Mild respiratory distress (less than half)• Asymptomatic (infrequent)• Severe life-threatening distress (least common)

Congenital lobar emphysema may be confused with pneumothorax or with a simple lung cyst or acquired cyst. In congenital lobar emphysema, there are bronchovascular markings within the overdistended lobe, and the adjacent lobe collapses are either caudad or cephalad but not medial, toward the hilum.

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•X Ray during the neonatal period, the emphysematous lobe may be opaque and homogeneous because of fetal lung fluid or it may show a diffuse reticular pattern that represents distended lymphatic channels filled with fetal lung fluid.

• As the fluid is absorbed, the affected segment or lobe becomes hyperlucent , from alveolar opacification to interstitial reticulation to general hyperlucency.

•Adjacent lobes and structures may be compressed by the emphysematous lobe, and sometimes ipsilateral and contralateral atelectasis may occur.

•The ipsilateral atelectatic lung is seen as a small, triangular density in the apical or supradiaphragmatic region

lucency in the right upper lobe (arrows) that displaces mediastinal structures to the left

Treatment– Surgical resection• Lobectomy

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Tracheobronchomegaly (Mounier-Kuhn syndrome)

•The condition was first recognized at autopsy by Czyhlarz in 1 897, 1932 Mounier-Kuhn associated the endoscopic And radiographic appearance of the markedly enlarged airway with recurrent respiratory tract infection

•Marked dilatation of the trachea and main bronchi, sometimes with tracheal diverticulosis, bronchiectasis, and recurrent lower respiratory tract infection.

•Etiology is uncertain.•Has an autosomal recessive type of inheritance•Predominantly occurs in men in their third and fourth decades of life.

Pathologic findingsAtrophy or absence of elastic fibers and thinning of muscle of the trachea and central bronchiRapid change to normal caliber at the 4th-5th order of bronchi

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Treatment –Physiotherapy to assist in clearing secretionsAppropriate antibiotics during infectious exacerbations

CT images of the thorax demonstrate marked dilatation of the trachea (T)and right (R) and left (L) main bronchi in this patient with Mounier-Kuhn syndrome

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Miscellaneous Bronchopulmonary Anomalies

Accessory & Heterotopic Pulmonary TissueDefined as presence of lung parenchyma over nad above normal complement of lung ,supplied by branches of pulmonary arterial and venous systems and connected by an airway to tracheobroncheal treeIts differs from extralobar sequestration as it doesn’t have systemic supply

Heterotopic Tissue with in lungHeterotopic skeletal muscle ,adrenal tissue , hepatic tissue . Thyroid and glial tissue can be found occasionally in Lung parenchyma

Horse shoe lungRare congenital malformation in which a isthmus of pulmonary parenchyma extends from right lung base across midline behind the pericardium and joins the posterobasal segments of right and left lungs Associated with scmitar syndrome

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Anatomical variants(Normal parenchyma)

• Pulmonary isomerismAnomaly of the number of lung lobes.Common variety - Right lung has 2 lobes, whereas the left has 3. May be associated with situs inversus, asplenia, polysplenia, and/or anomalous pulmonary drainage.

• Superior segment of lower lobe delineated by separate fissure

• Medial accessory left lower lobe

• Azygos lobe

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An azygos lobe is created when a laterally displaced azygos vein makes a deep fissure in the upper part of the lung during development. It is therefore not a true accessory lobe, but rather a normal variant appearance of the right upper lobe, which results from invagination of the azygos vein.An azygos lobe is found in 1% of anatomic specimens

AZYGOS LOBE

EmbryologyAn azygos lobe forms when the right posterior cardinal vein, one of the precursors of the azygos vein, fails to migrate over the apex of the lung and penetrates it instead, carrying along pleural layers that entrap a portion of the right upper lobe

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Conclusion•Although congenital lung malformations are rare, they are important disorders because they may lead to considerable morbidity and mortality (e.g., infection, hemorrhage, respiratory failure)

•Most congenital and developmental anomalies have certain characteristic imaging features. These features may aid in the differentiation from more sinister abnormalities.

•Delineating Adults with malformations is important , as increasing number of children in whom pediatric pulmonologists treat respiratory malformations, these patients eventually become adults with their malformation still in place.

•Keeping in mind these malformations while diagnosing and treating common respiratory problems .Like Infantile lobar hyperinflation can easily be confused with pneumothorax

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Babies are unpredictable. You never know what inconsistency they're going to catch you in next.