Congenital pulmonary airway malformation
Updates to Article Attributes
A congenital pulmonary airways malformation (CPAM) is a multicystic mass of segmental lung tissue with abnormal bronchial proliferation 2. CPAMs are considered part of the spectrum of bronchopulmonary foregut malformations and until recently were described as a congenital cystic adenomatoid malformation (CCAM).
Epidemiology
They account for ~25% of congenital lung lesions. The estimated incidence is approximately 1:1500-4000 live births and there is a male predominance.
Clinical presentation
The diagnosis is usually either made on antenatal ultrasound, or in the neonatal period on investigation of progressive respiratory distress 3-4. If large, they may cause pulmonary hypoplasia, with resultant poor prognosis.
In cases where the abnormality is small, the diagnosis may not be made for many years or even until adulthood. When it does become apparent it is usually as a result of recurrent chest infection 3-4.
Pathology
The condition results from failure of normal bronchoalveolar development with hamartomatous proliferation of terminal respiratory units in a gland-like pattern (adenomatoid) without proper alveolar formation.
Histologically, they are characterised by adenomatoid proliferation of bronchiole-like structures and macro- or microcysts lined by columnar or cuboidal epithelium and absence of cartilage and bronchial glands.
These lesions have intracystic communications and, unlike bronchogenic cysts, can also have a connection to the tracheobronchial tree.
Sub types
At least fourFive subtypes are currently classified, mainly according to cyst size.
-
type I
- most common: 70% of cases 3
- large cysts
- one or more dominant cysts: 2-10 cm in size
- may be surrounded by smaller cysts
-
type II
- 15-20% of cases 3
- cysts are <2 cm in diameter
- associated with other abnormalities
-
type III
- ~10% of cases
- microcysts: <5 mm in diameter
- typically involves an entire lobe
- has a poorer prognosis
-
type IV
- unlined cyst
- typically affects a single lobe
- Indistinguishable from Type I on imaging11
-
type 0
- very rare, lethal postnatally
- acinar dysgenesis or dysplasia11
- represents global arrest of lung development12
Location
Lesions are usually unilateral and involve a single lobe. Although there is no well-documented lobar predilection, they appear less frequently in the middle lobe 3.
Associations
- hybrid lesion: e.g. CPAM and pulmonary sequestration
- renal agenesis 7
Radiographic features
The appearance of CPAMs will vary depending on the type.
Antenatal ultrasound
CPAM appears as an isolated cystic or solid intrathoracic mass. A solid thoracic mass is usually indicative of a type III CPAM and is typically hyperechoic. There can be mass effect where the heart may appear displaced to the opposite side. Hydrops fetalis or polyhydramnios may develop and may be detected on ultrasound as ancillary sonographic features 3. Alternatively, the lesion may remain stable in size, or even regress 5.
Conventional radiography
Chest radiographs in type I and II CPAMs may demonstrate a multicystic (air-filled) lesion. Large lesions may cause mass effect with resultant mediastinal shift, depression, and even inversion of the diaphragm. In the early neonatal period the cysts may be completely or partially fluid-filled, in which case the lesion may appear solid or with air-fluid levels. Lesions may change in size on interval imaging (expand from collateral ventilation via pores of Kohn). Type III lesions appear solid.
CT
CT has a number of roles in the management of CPAMs. First, it more accurately delineates the location and extent of the lesion. Secondly, and most important in surgical candidates, CT angiography is able to identify systemic arterial supply if present.
Appearance reflects the underlying type, and a type III lesion can appear as a consolidation.
Treatment and prognosis
There can be wide spectrum in prognosis.
Surgery (elective lobectomy) is the treatment of choice in symptomatic patients, both in those presenting early with respiratory compromise and in those presenting later with recurrent infections 3. Type I lesions generally have the best prognosis.
In the setting of a small stable asymptomatic lesion, surgical excision is more controversial. Advocates for excision quote the reported risk of developing malignancies within the lesion (see above). An alternative approach is to watch and wait. There are reports of spontaneous regression, particularly in those serially followed up on antenatal ultrasound 7,10.
Complications
Potentialpostnatal complications include:
- recurrent pneumothorax
- haemopneumothorax
- pyopneumothorax
- possible incidence of certain malignancies, which include 3:
Potential in uterocomplications include:
- hydrops fetalis may rarely develop when there is severe compression of the fetal heart or great vessels
- compression of the normal fetal lung can also rarely cause pulmonary hypoplasia
Differential diagnosis
General imaging differential considerations include:
- bronchogenic cyst
- pulmonary sequestration (blood supply from arterial system)
- congenital diaphragmatic herniation
- congenital lobar emphysema (congenital lobar overinflation)
- localised congenital cystic bronchiectasis
For type I lesions on CT also consider:
- cicatrization collapse with scarring and traction bronchiectasis
-<p>A<strong> congenital pulmonary airways malformation (CPAM)</strong> is a multicystic mass of segmental lung tissue with abnormal bronchial proliferation <sup>2</sup>. CPAMs are considered part of the spectrum of <a href="/articles/bronchopulmonary-foregut-malformation">bronchopulmonary foregut malformations</a> and until recently were described as a <strong>congenital cystic adenomatoid malformation (CCAM)</strong>.</p><h4>Epidemiology</h4><p>They account for ~25% of congenital lung lesions. The estimated incidence is approximately 1:1500-4000 live births and there is a male predominance.</p><h4>Clinical presentation</h4><p>The diagnosis is usually either made on antenatal ultrasound, or in the neonatal period on investigation of progressive respiratory distress <sup>3-4</sup>. If large, they may cause <a href="/articles/pulmonary-hypoplasia">pulmonary hypoplasia</a>, with resultant poor prognosis. </p><p>In cases where the abnormality is small, the diagnosis may not be made for many years or even until adulthood. When it does become apparent it is usually as a result of recurrent chest infection <sup>3-4</sup>. </p><h4>Pathology</h4><p>The condition results from failure of normal bronchoalveolar development with hamartomatous proliferation of terminal respiratory units in a gland-like pattern (adenomatoid) without proper alveolar formation.</p><p>Histologically, they are characterised by adenomatoid proliferation of bronchiole-like structures and macro- or microcysts lined by columnar or cuboidal epithelium and absence of cartilage and bronchial glands. </p><p>These lesions have intracystic communications and, unlike bronchogenic cysts, can also have a connection to the tracheobronchial tree.</p><h5>Sub types</h5><p>At least four subtypes are currently classified, mainly according to cyst size.</p><ul>- +<p>A<strong> congenital pulmonary airways malformation (CPAM)</strong> is a multicystic mass of segmental lung tissue with abnormal bronchial proliferation <sup>2</sup>. CPAMs are considered part of the spectrum of <a href="/articles/bronchopulmonary-foregut-malformation">bronchopulmonary foregut malformations</a> and until recently were described as a <strong>congenital cystic adenomatoid malformation (CCAM)</strong>.</p><h4>Epidemiology</h4><p>They account for ~25% of congenital lung lesions. The estimated incidence is approximately 1:1500-4000 live births and there is a male predominance.</p><h4>Clinical presentation</h4><p>The diagnosis is usually either made on antenatal ultrasound, or in the neonatal period on investigation of progressive respiratory distress <sup>3-4</sup>. If large, they may cause <a href="/articles/pulmonary-hypoplasia">pulmonary hypoplasia</a>, with resultant poor prognosis.</p><p>In cases where the abnormality is small, the diagnosis may not be made for many years or even until adulthood. When it does become apparent it is usually as a result of recurrent chest infection <sup>3-4</sup>.</p><h4>Pathology</h4><p>The condition results from failure of normal bronchoalveolar development with hamartomatous proliferation of terminal respiratory units in a gland-like pattern (adenomatoid) without proper alveolar formation.</p><p>Histologically, they are characterised by adenomatoid proliferation of bronchiole-like structures and macro- or microcysts lined by columnar or cuboidal epithelium and absence of cartilage and bronchial glands.</p><p>These lesions have intracystic communications and, unlike bronchogenic cysts, can also have a connection to the tracheobronchial tree.</p><h5>Sub types</h5><p>Five subtypes are currently classified, mainly according to cyst size.</p><ul>
- +<li>Indistinguishable from Type I on imaging<sup>11</sup>
- +</li>
-</ul><h5>Location</h5><p>Lesions are usually unilateral and involve a single lobe. Although there is no well-documented lobar predilection, they appear less frequently in the middle lobe <sup>3</sup>. </p><h5>Associations</h5><ul>- +<li>
- +<strong>type 0</strong><ul>
- +<li>very rare, lethal postnatally</li>
- +<li>acinar dysgenesis or dysplasia<sup>11</sup>
- +</li>
- +<li>represents global arrest of lung development<sup>12</sup>
- +</li>
- +</ul>
- +</li>
- +</ul><h5>Location</h5><p>Lesions are usually unilateral and involve a single lobe. Although there is no well-documented lobar predilection, they appear less frequently in the middle lobe <sup>3</sup>.</p><h5>Associations</h5><ul>
-</ul><h4>Radiographic features</h4><p>The appearance of CPAMs will vary depending on the type. </p><h5>Antenatal ultrasound </h5><p>CPAM appears as an isolated cystic or solid intrathoracic mass. A solid thoracic mass is usually indicative of a type III CPAM and is typically hyperechoic. There can be mass effect where the heart may appear displaced to the opposite side. <a href="/articles/hydrops-foetalis">Hydrops fetalis</a> or <a href="/articles/polyhydramnios">polyhydramnios</a> may develop <sup> </sup>and may be detected on ultrasound as ancillary sonographic features <sup>3</sup>. Alternatively, the lesion may remain stable in size, or even regress <sup>5</sup>.</p><h5>Conventional radiography</h5><p>Chest radiographs in type I and II CPAMs may demonstrate a multicystic (air-filled) lesion. Large lesions may cause mass effect with resultant mediastinal shift, depression, and even inversion of the diaphragm. In the early neonatal period the cysts may be completely or partially fluid-filled, in which case the lesion may appear solid or with air-fluid levels. Lesions may change in size on interval imaging (expand from collateral ventilation via <a href="/articles/pores-of-kohn">pores of Kohn</a>). Type III lesions appear solid. </p><h5>CT</h5><p>CT has a number of roles in the management of CPAMs. First, it more accurately delineates the location and extent of the lesion. Secondly, and most important in surgical candidates, CT angiography is able to identify systemic arterial supply if present.</p><p>Appearance reflects the underlying type, and a type III lesion can appear as a consolidation. </p><h4>Treatment and prognosis</h4><p>There can be wide spectrum in prognosis.</p><p>Surgery (elective lobectomy) is the treatment of choice in symptomatic patients, both in those presenting early with respiratory compromise and in those presenting later with recurrent infections <sup>3</sup>. Type I lesions generally have the best prognosis.</p><p>In the setting of a small stable asymptomatic lesion, surgical excision is more controversial. Advocates for excision quote the reported risk of developing malignancies within the lesion (see above). An alternative approach is to watch and wait. There are reports of spontaneous regression, particularly in those serially followed up on antenatal ultrasound <sup>7,10</sup>.</p><h5>Complications</h5><p>Potential<strong> </strong>postnatal complications include:</p><ul>- +</ul><h4>Radiographic features</h4><p>The appearance of CPAMs will vary depending on the type.</p><h5>Antenatal ultrasound</h5><p>CPAM appears as an isolated cystic or solid intrathoracic mass. A solid thoracic mass is usually indicative of a type III CPAM and is typically hyperechoic. There can be mass effect where the heart may appear displaced to the opposite side. <a href="/articles/hydrops-foetalis">Hydrops fetalis</a> or <a href="/articles/polyhydramnios">polyhydramnios</a> may develop <sup> </sup>and may be detected on ultrasound as ancillary sonographic features <sup>3</sup>. Alternatively, the lesion may remain stable in size, or even regress <sup>5</sup>.</p><h5>Conventional radiography</h5><p>Chest radiographs in type I and II CPAMs may demonstrate a multicystic (air-filled) lesion. Large lesions may cause mass effect with resultant mediastinal shift, depression, and even inversion of the diaphragm. In the early neonatal period the cysts may be completely or partially fluid-filled, in which case the lesion may appear solid or with air-fluid levels. Lesions may change in size on interval imaging (expand from collateral ventilation via <a href="/articles/pores-of-kohn">pores of Kohn</a>). Type III lesions appear solid.</p><h5>CT</h5><p>CT has a number of roles in the management of CPAMs. First, it more accurately delineates the location and extent of the lesion. Secondly, and most important in surgical candidates, CT angiography is able to identify systemic arterial supply if present.</p><p>Appearance reflects the underlying type, and a type III lesion can appear as a consolidation.</p><h4>Treatment and prognosis</h4><p>There can be wide spectrum in prognosis.</p><p>Surgery (elective lobectomy) is the treatment of choice in symptomatic patients, both in those presenting early with respiratory compromise and in those presenting later with recurrent infections <sup>3</sup>. Type I lesions generally have the best prognosis.</p><p>In the setting of a small stable asymptomatic lesion, surgical excision is more controversial. Advocates for excision quote the reported risk of developing malignancies within the lesion (see above). An alternative approach is to watch and wait. There are reports of spontaneous regression, particularly in those serially followed up on antenatal ultrasound <sup>7,10</sup>.</p><h5>Complications</h5><p>Potential<strong> </strong>postnatal complications include:</p><ul>
-<li><a href="/articles/adenocarcinoma-in-situ-and-minimally-invasive-adenocarcinoma-in-lung">bronchoalveolar carcinoma</a></li>- +<li><a href="/articles/adenocarcinoma-in-situ-minimally-invasive-adenocarcinoma-and-invasive-adenocarcinoma-of-lung">bronchoalveolar carcinoma</a></li>
-<li><a href="/articles/congenital-lobar-overinflation">congenital lobar emphysema</a></li>- +<li>
- +<a href="/articles/congenital-lobar-overinflation">congenital lobar emphysema</a> (congenital lobar overinflation)</li>
References changed:
- 11. Biyyam DR, Chapman T, Ferguson MR et-al. Congenital lung abnormalities: embryologic features, prenatal diagnosis, and postnatal radiologic-pathologic correlation. Radiographics. 2010;30 (6): 1721-38. <a href="http://dx.doi.org/10.1148/rg.306105508">doi:10.1148/rg.306105508</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/21071385">Pubmed citation</a><span class="auto"></span>
- 12. Kao SW, Zuppan CW, Young LW. AIRP best cases in radiologic-pathologic correlation: type 2 congenital cystic adenomatoid malformation (type 2 congenital pulmonary airway malformation). Radiographics. 2011;31 (3): 743-8. <a href="http://dx.doi.org/10.1148/rg.313105162">doi:10.1148/rg.313105162</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/21571654">Pubmed citation</a><span class="auto"></span>