Paediatric Chest

Definition

• Previously known as congenital cystic adenomatoid malformation (CCAM)

• A rare lesion caused by hamartomatous proliferation of the terminal bronchioles at the expense of alveolar development ▸ it is characterized by a multicystic mass of pulmonary tissue with proliferation of the bronchiolar structures

• It is usually unilobar and communicates with a normal tracheobronchial tree ▸ it receives its blood supply from a normal pulmonary artery and vein ▸ it may compress the contralateral lung (resulting in hypoplasia)

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    Type 1 – macrocystic (65%): variable cysts with at least one dominant cyst present (up to 10 cm) ▸ this has a good prognosis (and an infrequent association with other congenital abnormalities)

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    Type 2 – microcystic (10–15%) : smaller more uniform cysts (up to 2 cm) ▸ congenital malformations are common (50%)

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    Type 3 – mixed (~8%) : solid-appearing microcysts (1.5 cm) with an associated mass effect (giving a ground-glass appearance on CT) ▸ it has a poor prognosis due to the associated congenital malformations and severe respiratory compromise ▸ nearly always mediastinal shift

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    Type 4 (10–15%): large cysts (up to 7 cm) ▸ may be a precursor of pleuropulmonary blastoma

Clinical Presentation

• Neonatal respiratory distress or it can present in older children ▸ symptoms are due to a combination of obstructive emphysema, mediastinal shift and infection

Radiological Features

• During the first few hours of life a CCAM will appear as a soft tissue mass (due to the retained lung fluid within it) which may cause mediastinal shift ▸ once this fluid has been reabsorbed it will be replaced by an air-filled cystic lesion

Pearls

• CPAMs can communicate with the airways ▸ infected (30%) ▸ blood supply from the pulmonary artery with drainage via pulmonary veins

• There is a variable natural history and prognosis (larger lesions have a worse prognosis)

• Lesions that are identified prenatally may involute in utero

• Treatment: early surgical removal may be required if there is severe pulmonary compromise (and if the contralateral lung is not hypoplastic)

Definition

• This anomaly shares some features with sequestration except:

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    The lung is normally connected to the bronchial tree

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    The vein draining the affected lobe (usually the right lower lobe) drains into the IVC or portal vein (rather than the left atrium)

• There is usually an absent or small pulmonary artery perfusing the abnormal lung

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    The arterial supply is partly or wholly from the thoracic or abdominal aorta, or the coeliac axis

Clinical Presentation

• It may be asymptomatic or present with features of a left-to-right shunt

Radiological Features

• A small ipsilateral lung with ipsilateral mediastinal shift

• The abnormal pulmonary vein is seen draining down and enlarging towards the diaphragm in the shape of a ‘scimitar’ sword

Definition

• A congenital mass of aberrant pulmonary tissue that has no normal connection with the bronchial tree or pulmonary arteries ▸ lesions are defined as either intra- or extralobar

• It derives its arterial supply from either the thoracic or abdominal aorta ▸ its venous drainage can either be via the pulmonary or systemic veins

Clinical Presentation

• It can present at birth or in an older child (depending on the type) with recurrent focal infections, bronchiectasis, haemoptysis or as an asymptomatic pulmonary mass

Radiological Features

Pearl

• Extralobar sequestration can be located below the diaphragm and mimic a neuroblastoma or adrenal haemorrhage

	Intralobar sequestration	Extralobar sequestration
Prevalence	75%	25%
Age at presentation	Older children ▸ adults	Neonates
Clinical presentation	Symptoms of pneumonia (recurrent or refractory to treatment)	Dyspnoea, cyanosis and feeding difficulties
Relationship to the native lung	Located within the native lung with no separate pleural lining	External to the native lung with its own pleural lining
Aeration of the affected segment	May be aeration of sequestered lung via collateral air drift (Kohn pores)	No aeration (due to its own pleural envelope preventing collateral air drift ▸ rarely air may be present due to communication with the GI tract)
Common location	Left lower lobe (60%)	Left sided (98%) between the lower lobe and diaphragm
Arterial supply	Thoracic > abdominal aorta	Thoracic > abdominal aorta
Venous drainage	Pulmonary veins	Systemic veins: IVC, azygous and portal veins
Anomalies	Uncommon (12%): skeletal deformities ▸ diaphragmatic hernia ▸ cardiovascular and renal anomalies	Common (65%): congenital lobar emphysema ▸ type 2 CCAM ▸ pulmonary hypoplasia ▸ bronchogenic cysts ▸ diaphragmatic hernia ▸ cardiovascular anomalies