Congenital pulmonary airway malformation: case report

Background

Congenital pulmonary airway malformation is a hamartomatous lesion of the lung,with an incidence of about 1 in 25,000-35,000 live births and prenatal diagnosis is feasible in the second trimester.

Case(s)

Second trimester ultrasonographic examination showed bilateral large hyperechogenic intrathoracal structures and ascites in a fetus at the 23rd gestational week.Autopsy examination after termination of pregnancy revealed randomly distributed irregular bronchiole-like structures and separate dilated alveol-like structures in fetal lungs.

Conclusion

Congenital pulmonary airway malformation is a rare defect of the lung which can be suspected by typical sonographic aspect and related systemic changes.Biopsy or specimen evaluation can permit hystopathologic diagnosis.

Keywords

Congenital pulmonary airway malformation (CPMA), congenital cystic adenomatoid malformation (CCAM), autopsy

Introduction

Congenital pulmonary airway malformation has first been described by Chin and Tang in 1949 (1). It is a rare hamartoma of the lungs that occur from unsystematic spread of tubular bronchioles and enlarged alveolar tissue (2). Congenital pulmonary airway malformation is mostly diagnosed in neonatal period. More than 90% of these cases have been reported to be diagnosed in the first two years of life. This malformation can spontaneously regress, increase in size or cause non-immune hydrops fetalis (3). Therefore, the differential diagnosis should be made when echogenic lesions seen in the fetal lung at the prenatal period. Here we present a case of congenital pulmonary airway malformation which definitive diagnosis was made postnatally by autopsy.

Case(s)

Thirty years of age, gravida 5, para 4, abortion 0, live birth 3 case who has married with a relative. Bilateral large thoracic hyperechogenic lesions, fetal abdominal ascites, head and skin edema were observed in prenatal ultrasound at the 23rd week of gestation. The fetus was diagnosed as having non-immune hydrops fetalis (Figure 1). Medical abortion was performed due to family’s decision. The APGAR score of the male fetus was 0. Macroscopically, the baby was 1100 gram in weight, 35 cm tall. Laringeotracheal atresia was diagnosed. Placenta was 320 gram in weight and had normal appearance. Both lungs were large and hard. Both lungs were 8x4x3 cm (Figure 2). Autopsy revealed many microcysts (0.1-0.2 mm), randomly spread immature bronchioles and large alveoli in the lung tissue. Microscopically, bronchioles and alveoli like-tissue with many cuboidal epithelial cells in mesenchymal interstitial tissue were seen (Figure 3). The histopathological diagnosis of congenital pulmonary airway malformation type III was made according these findings.

Discussion

Congenital pulmonary airway malformation is a rare hamartomatous lesion of the lung that characterized with abnormal development of alveoli and hyperplastic terminal bronchioles due to abnormal embryogenesis at 6 to 7th week of gestation (4). It has been reported to be seen in 1 of 25.000-35.000 live births (5). Stocker et al has described three different type of congenital cystic adenomatoid malformation of the lung in 1977 (6). Recently, Stocker has added two more type according to anatomic and microscopic properties of pulmonary airway, and has used congenital pulmonary airway malformation term for this anomaly (7). It may be associated with pulmonary hypoplasia, heart failure, polihydramnios, mediastinal shift and particularly non-immune fetal hydrops. However, this lesion may rarely regress spontaneously at prenatal period (8). Aksoy et al have described a congenital pulmonary airway malformation case associated with other congenital anomalies (9). In our case, we observed non-immune hydrops associated with the pathology. Recently, prenatal magnetic resonance imaging has been recommended for diagnosis and follows up of these lesions. It is important not only for diagnosis but also for early treatment of such malformations (5).
Congenital pulmonary airway malformation is characterized with abnormal differentiation of immature bronchioles and abnormal breath pattern during morphogenesis of the lung. The type of these lesions was first described by Chin and Tang in 1949 (1). The types of congenital pulmonary airway malformation:
Type 0: Acinary dysplasia – tracheobronchiolar origin
Type I: Bronchi/bronchiole originated multiple large cystic type
Type II: Bronchiole originated multiple small cystic type
Type III: Bronchiole/alveol originated multiple small cystic or solid type
Type IV: Distal acinary originated peripheral cystic type (7).
Type III is seen in 5% of patients. The majority of type III occurs in boys. Mortality rate is high in type III patients due to polihydramnios and generalized fetal edema. Large parenchymal mass generally is unilateral, located in one lobe of the lung, and cause mediastinal shift and pulmonary hypoplasia. In our case, the lesion was bilateral and located in the whole lung.
Macroscopically, the diameter of cysts is rarely greater than 0.2 mm and bronchi-like large tissue is seen between cysts. These lesions have named as adenomatoid due to their microscopic appearance of unsystematic spread of bronchioles with cuboidal epithelial cells and alveoli-like tissue (10). Our case had typical properties of type III congenital pulmonary airway malformation.

Conclusion

In conclusion, congenital pulmonary airway malformation is a rare pathology. It should be kept in mind that non-immune hydrops fetalis patients may be associated with congenital pulmonary airway malformation. The differential diagnosis can be done by histopathological evaluation.

References

1.Ch'in KY, Tang MY. Congenital adenomatoid malformation of one lobe of a lung with general anasarca. Arch. Pathol. Lab. Med. 1949; 48:221–9.
2.Rajiv C, Dharmendra S, Paras K, Siddharth S, Choudhury SR, Jain J, et al. Congenital cystic adenomatoid malformation associated with ipsilateral eventration of the diaphragm. Clin Brief 2006; 73: 832-4.
3.Janka GE, Schneider EM. Modern management of children with hemophagocytic lymphohistio-cytosis. Br J Hematol 2004; 124: 4-14.
4.Kawamura M, Itoh H, Yamada S, Yura S, Katsuya S,Kosaka K, Tatsumi K, et al. Spontaneous regression of congenital cystic adenomatoid malformation of the lung: Longitudinal examinations by magnetic resonance imaging. Congenit Anom (Kyoto) 2005; 45: 157-60.
5.Laberge JM, Flageole H, Pugash D, Khalife S, Blair G, Fliatrault D, et al. Outcome of the prenatally diagnosed congenital cystic adenomatoid lung malformation: A Canadian experience. Fetal Diagn Ther 2001;16:178–86.
6.Stocker JT, Madewell JE, Drake RM. Congenital cystic adenomatoid malformation of the lung. Classification and morphologic spectrum. Hum Pathol 1977; 8: 155–71.
7.Stocker JT. Congenital pulmonary airway malformation: A new name and an expanded classification of congenital cystic adenomatoid malformations of the lung. Histopathology 2002; 41: 424–31.
8.De Santis M, Masini L, Noia G, Cavaliere AF, Oliva N, Caruso A. Congenital cystic adenomatoid malformation of the lung: Antenatal ultrasound findings and fetal neonatal outcome. Fifteen years of experience. Fetal Diagn Ther 2000; 15: 246–50.
9.Aksoy F, Ramazanoğlu R,Şen C.Congenital cystic adenomatoid malformation type III associated with congenital anomalies. Perinatoloji Dergisi 2000; 8: 123-5.
10.Gilbert-Barness E. The respiratory system. In: Gilbert-Barness E, (ed). Potter's pathology of the fetus and infant. 1997; St Louis: Mosby-Year Book. 712p.

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	Figure-2 Microscopic appearance of large lungs
	Figure-3 Microscopic appearance of lung tissue
	Figure-1 Ultrasonographic appearance