Congenital cystic adenomatoid malformation (CCAM), or congenital pulmonary airway malformation (CPAM) as it is now called, is one of the most common congenital pulmonary surgical disorders in children. With the development and advancement of prenatal ultrasound techniques, the vast majority of this case can be diagnosed prenatally. The usual prenatal report of the findings is also the most familiar term for all parents: cystic adenoma of the lung. Fetal cystic adenoma of the lung is not a tumor, but a malformation of lung development that appears to be a tumor on prenatal ultrasound, a benign condition that can be cured by minimally invasive surgical treatment. The effects of CCAM on children are mainly manifested in three aspects: 1. Compression of surrounding organs: Since the malformation manifests as cysts of different sizes and numbers, when the cysts are too large, they can push and compress the normal organs in the chest cavity. In severe cases, it can have corresponding effects on the fetus or baby. In fetal life, if the cysts are too large, they can compress the inferior vena cava of the fetus, causing impairment of inferior vena cava return and resulting in hydrops fetalis (fetal edema). Persistent fetal edema is the most serious complication of CCAM, but its incidence is very low and, even if it occurs in some cases, it mostly resolves spontaneously at a later stage. Only in a very few cases does persistent fetal edema develop and even endanger the life of the fetus, requiring fetal surgical management. After the prenatal detection of CCAM, the most important concern of parents-to-be is: does their baby have hydrops fetalis? How can they tell and predict whether their baby will have it or not? If it does occur, what should be done? First, as mentioned earlier, the incidence of persistent fetal edema, which can really have serious effects on the fetus, is very low, and the incidence varies from center to center worldwide. Second, it is difficult to accurately predict fetal edema, and there is a lack of specific indicators. Current indicators used for prediction include: lung/thoracic cross-sectional area ratio (L/T value) and cystic volume ratio (CVR). Among them, the one that has been applied more often is the CVR, which is the ratio of cyst to fetal head circumference. Some foreign studies concluded that there is an 80% chance of fetal edema when CVR > 1.6. Other studies have concluded that this data is not sensitive and that a high proportion of cases of fetal edema resolve on their own. However, children with fetal edema all have a substantially elevated CVR, with one study finding a mean CVR as high as 3.1 compared to a normal fetal CVR value of around 0.74. Finally, for the very few children who do develop persistent fetal edema, surgical management of the fetus or surgical intervention in the delivery room after early delivery may be an option, depending on the severity of the situation. Surgical management of the fetus is generally used for earlier and more severe cases of fetal edema, especially if the fetal edema is detected before 32 weeks. Management includes: fetal surgery (now less recommended); ultrasound-guided cyst puncture for decompression; and thoracic-amniotic diversion. The latter two are mainly used in the treatment of large, solitary cysts. Some babies with large cysts do not develop fetal edema during the fetal period. After birth, because the cyst pushes on the mediastinum of the heart and squeezes the normal lungs, respiratory and circulatory symptoms such as shortness of breath and cyanosis are evident. At this time, it should be actively evaluated and treated. After prompt completion of all preoperative tests, the affected lung or cyst is surgically removed in an emergency. In general, the incidence of severe compression symptoms due to oversized cysts is low, and from the results of our current case observation, the proportion of children with significant symptoms due to compression before or at birth is less than 2%, and the vast majority of babies can be delivered safely and normally. 2. Infection: The vast majority of babies born with no obvious symptoms are called asymptomatic CCAM, which is anatomically characterized by a cystic airway that connects to the airway of the normal lung. Because the malformed part of the lung tissue does not have the structure of normal lung tissue, at the same time, when the cyst is large, it will produce extrusion of normal lung tissue, both of which will lead to poor drainage of the cyst or its surrounding lung tissue, which will easily lead to repeated lung infections and pneumonia after the baby is born. Also, due to the presence of malformed lung tissue, pneumonia in babies is more difficult to cure and more likely to recur than pneumonia that occurs in normal children, and is more severe and difficult to treat one at a time, with a shorter interval than another. In addition, when infection occurs, it easily leads to adhesions in the chest cavity, and when the adhesions are severe, it greatly increases the difficulty and risk of surgical treatment, and some cases cannot be treated by minimally invasive thoracoscopic surgery and can only be treated by open surgery. At present, a large number of studies at home and abroad have found that thoracic adhesions due to repeated preoperative infections are the most important factor leading to the conversion of minimally invasive thoracoscopic surgery to open surgery. Therefore, unlike compression symptoms, infection is a complication that most children with CCAM are likely to encounter after birth and requires active treatment and management. 3. Cancer: Because CCAM is a deformed, abnormal lung tissue and is prone to repeated infections, these two factors lead to a greater risk of cancer in children with CCAM when they grow up. Because of this, in order to avoid cancerous changes, surgery should be performed at the right time after birth, depending on the baby’s specific condition. In summary, CCAM is a common congenital malformation of lung development and is a benign disease. Due to the development of prenatal ultrasound technology, the vast majority of them can be detected prenatally. The majority of diagnosed CCAM cases are delivered normally and are asymptomatic after birth, requiring only periodic review and avoidance of respiratory infections. Depending on the condition of the baby after birth and the results of the examination, the right time for surgery is chosen and the affected lung is removed by minimally invasive thoracoscopic surgery, and all but a very few special types of children can recover and reach the healthy state of a normal baby.