Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Congenital pulmonary airway malformation (CPAM) combined with pneumonia
- Radiologic Findings
- On initial chest radiograph and chest CT, multiple well-defined thin walled cysts and air trapping with hypovascularity are seen in the right lower lobe.
Chest CT taken 2 years later demonstrates increased cystic lesions with air-fluid levels.
The patient underwent right lower lobectomy and was pathologically diagnosed as CPAM(type 1) combined with pneumonia.
- Brief Review
- Congenital pulmonary airway malformation (CPAM), previously known as congenital cystic adenomatoid malformation (CCAM), is a rare developmental anomaly of the lower respiratory tract (1-5). They are still the most common congenital lung lesion. CPAMs occurs sporadically. Their formation is not related to maternal factor such as race, age, or exposures.
Congenital pulmonary airway malformations (CPAMs) result from abnormalities of branching morphogenesis of the lung. The different types of CPAMs are thought to originate at different levels of the tracheobronchial tree and at different stages of lung development, possibly influenced by in utero airway obstruction and/or atresia (6-8).
Congenital pulmonary airway malformation (CPAMs) are hamartous lesions that are comprised of cystic and adenomatous elements arising from tracheal, bronchial, bronchiolar, or alveolar tissue. CPAMs have connections with the tracheobronchial tree, although the connecting bronchi are usually not normal. The arterial supply and venous drainage from the lesion are from the lesion are from the pulmonary circulation, though vascular connections to the systemic circulation have been reported. CPAMs are equally distributed between the right and left lungs and can arise in all lobes. The CPAMs that present during adulthood tent to be in the lower lobe (9).
**Classification
In 1997, Stocker et al (11), using specific gross and histologic criteria, classified CCAMs, which they subdesignated as type I (macrocystic, >2cm), type II (multiple smaller cysts), and type III (solid with microscopic cysts). In 2001, Stocker (12), expanded that classification, adding type 0 lesion (previously reported as acinar dysplasia of the lung) and type 4 lesions (a type of peripheral lung cyst manifesting with pneumothorax).
Type 0 is the rarest form, comprising only 1 to 3 percent of cases. The cysts are small, with a maximum diameter of 0.5cm, and are lined with ciliated pseudostratified epithelium. This is a diffuse malformation that involves the entire lung. Gas exchange is severely impaired, and affected infants die at birth(6).
Type 1 is the most common form of CPAM, comprising 60 to 70 percent(6). They are comprised of distinct thin-walled distinct cysts 2 to 10 cm in diameter. The cysts are usually single but may be multiloculated. They are lined with ciliated pseudostratified columnar epithelium and the walls contain smooth muscle and elastic tissue. The clinical presentation of type 1 of CPAMs depends primary on the size of the cysts.
Type 2 lesions comprise 15 to 20 percent of CPAMs. They consist of multiple cysts 0.5 to 2cm in diameter and solid areas that blend into adjacent normal tissue. The cysts resemble dilated terminal bronchioles and are lined with ciliated cuboidal or columnar epithelium. Other congenital anomalies are observed in patients with type 2 CPAM in up to 60 percent of cases(1, 6). These malformations include esophageal atresia with tracheoesophageal fistula, bilateral renal agenesis or dysgenesis, intestinal atresia, other pulmonary malformations, and diaphragmatic, cardiac, central nervous system, and bony anomalies.
Type 3 CPAMs comprise 5 to 10 percent of CPAMs. They are often very large, and can involve and an entire lobe or several lobes. They have an acinar origin and consist of adenomatoid proliferation of distal airways or airspaces. They can be a mixture of cystic and solid tissue or be entirely solid. The numerous small cysts are less than 0.5 cm in diameter and are lined with nonciliated cuboidal epithelium.
Type 4 lesions comprise 10 to 15 percent of CPAMs. The cysts have a maximum diameter of 7 cm and consist of nonciliated, flattened, alveolar lining cells, with no mucus cells or skelectal muscle. Type 4 CPAMs may present at birth or in childhood, often with tension pneumothorax or infection, but they may also be identified as incidental findings in asymptomatic patients. Importantly, this type of CPAM is strongly associated with malignancy, especially with pleuropulmonary blastoma(PPB).
- References
- 1. Stocker JT, Drake RM, Madewell JE. Cystic and congenital lung disease in the newborn. Perspect Pediatr Pathol 1978; 4:93.
2. Landing BH, Dixon LG. Congenital malformations and genetic disorders of the respiratory tract (larynx, trachea, bronchi, and lungs). Am Rev Respir Dis 1979; 120:151.
3. Kravitz RM. Congenital malformations of the lung. Pediatr Clin North Am 1994; 41:453.
4. Albers GM, Wood RE. Update in the diagnosis and management of congenital malformations of the airway and lung. Clin Pulm Med 1995; 2:368.
5. Shanti CM, Klein MD. Cystic lung disease. Semin Pediatr Surg 2008; 17:2.
6. Priest JR, Williams GM, Hill DA, et al. Pulmonary cysts in early childhood and the risk of malignancy. Pediatr Pulmonol 2009; 44:14.
7. Kunisaki SM, Fauza DO, Nemes LP, et al. Bronchial atresia: the hidden pathology within a spectrum of prenatally diagnosed lung masses. J Pediatr Surg 2006; 41:61.
8. Riedlinger WF, Vargas SO, Jennings RW, et al. Bronchial atresia is common to extralobar sequestration, intralobar sequestration, congenital cystic adenomatoid malformation, and lobar emphysema. Pediatr Dev Pathol 2006; 9:361.
9. Zylak CJ, Eyler WR, Spizarny DL, Stone CH. Developmental lung anomalies in the adult: radiologic-pathologic correlation. Radiographics 2002; 22 Spec No:S25.
10. Stocker JT, Madewell JE, Drake RM. Congenital cystic adenomatoid malformation of the lung. Classification and morphologic spectrum. Hum Pathol 1977; 8:155.
11. Stocker JT. Congenital pulmonary airway malformation - a new name for and an expanded classification of congenital cystic adenomatoid malformation of the lung. Histopathology 2002; 41:424.
- Please refer to
- Case 135 Case 430 Case 647
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- Keywords
- Lung, Congenital,