What causes pulmonary cystadenoma?

The lungs are very important organs in the human body. As soon as a child is born, the various functions of the lungs need to be checked to ensure that there are no problems with the lungs. Among the common diseases that affect lung function, pulmonary cystadenoma is one of the more harmful ones and is a congenital disease. Therefore, understanding the cause of the disease will help us better prevent it. So, what causes pulmonary cystadenoma? Let’s take a look below.

CCAM is caused by excessive growth of the fetal terminal bronchi, forming a lesion with clear boundaries in the lung parenchyma, often involving part or all of a lobe, and can involve one or both sides of the lung parenchyma. Mediastinal shift may occur in 90% of cases.

The exact cause of CCAM is still unclear. The most common view is that CCAM is a hamartoma-like lesion, which is accompanied by excessive developmental abnormalities of one or more tissue components. CCAM may be caused by unknown factors during fetal lung bud development, which may hinder local lung development and lead to overgrowth of developed lung tissue. Chen HW summarized 16 cases of prenatally diagnosed fetal lung diseases, of which 8 cases (8/16) were CCAM, 5 cases (5/16) were BPS, and 3 cases (3/16) were mixed lesions of CCAM and BPS. The appearance of mixed lesions suggested that CCAM and BPS may have developed from the same original germ base.

Moerman et al. found from the autopsy of 4 cases of CCAM that each case had segmental bronchial absence or atresia, which provided further evidence for the hypothesis that bronchial atresia is the primary defect in the occurrence of CCAM. They also proposed that the primary defect is a developmental restriction, arrest or defect in the process of bronchopulmonary budding and branching, causing bronchial atresia, and the atresia leads to the absence of bronchi. The study speculates that the defect can occur as early as 24 days of embryonic development, or as late as 19 weeks of gestation. Cass et al. found that compared with normal fetal lungs at the corresponding gestational age, the cell proliferation index of CCAM lesions increased by 2 times, and the apoptotic bodies were only 1/5. Therefore, they assumed that CCAM is the result of an imbalance between cell proliferation and apoptosis during lung development.

Fromont-Hankard et al. proposed that abnormal expression of glial cell-derived neurotrophic factor (GDNF) leads to lung development arrest. Some studies have also shown that the enhanced expression of the Hoxb-5 gene is related to the occurrence of CCAM. Kulwa reported a case of fetal CCAM whose mother had a clear history of alcohol abuse during pregnancy, suggesting that alcohol may act as a teratogen and reduce the production of retinoic acid (RA) through the mediation of P450 and the inhibition of alcohol dehydrogenase, leading to the occurrence of CCAM. The above literature reports provide a basis for further elucidation of the pathogenesis of CCAM.