lesions are cystic in only three out of five types and adenomatoid in only one type CPAM is relatively rare affecting one in 25,000 to 35,000 pregnancies overall it is the most common type of congenital lung lesion CPAM is not hereditary so it usually does not occur in families. There are no predictive factors such as sex, ethnicity, maternal age, delivery disease consists of replacement of a portion of the lung by non-functioning cystic lesion There is no genetic predisposition with the exception of type 4 malformationz There is no genetic predisposition with the exception of type 4 malformation type 4 have an association with familial pluropulmonary blastoma syndrome familial pluripulmonary plastoma have a mutation of the Dicer1 gene CPAM is a developmental non-hereditary hamartomatous abnormality of the lung. It contains cystic and adenomatous elements and it is connected to the tracheobronchial tree usually it is unilateral and limited to one lobe blood supply from the pulmonary circulation means this segment or this lesion will be supplied by deoxygenated The lesion is caused by an arrested alveolar development associated with proliferation of bronchial-like structures in the affected lobe. lined by columnar to cubical epithelium and they have soft wall So air enters and then trapped causing cystic dilatation of these bronchiole-like structures ---------------------- stoker classification of CPAM five types of CPAM classified pathologically according to the level of the insult to the airway and the different stages of lung development type O is tracheobronchial, type 1 is the bronchial type, type 2 bronchiolar and type 3 alveolar duct and type 4 distal acinar Type 0: one to three percent of the cases site of insult is the trachea and proximal bronchi both lungs are affected Formerly this type was known as congenital acinar dysplasia of the lungs incompatible with life Type 1-C-PAM accounts for 60 to 70 percent the most common type arise from the distal bronchi or proximal bronchioles restricted to single lobe of the lung characterized by single or multiple large cysts 3 to 10 centimeter in diameter and surrounded by smaller cysts and compressed normal parenchyma. Associcated with Broncho-alveolar Carcinoma C-PAM type 2. Type 2 is the bronchiolar type 10 to 15 percent of the cases site of insult is the bronchioles usually associated with other congenital anomalies bilateral renal agenesis congenital anomalies in the heart or a brain syringomyelia bilateral agenesis or cardiovascular anomalies type 2 is called the medium cyst type cyst of 0.5 to 2 centimeter in diameter CPAM-type 3 type 3 is the alveolar type account for five percent of the cases arise from the alveolar ducts this type is solid may take the whole lobe/more than one lobe of the lung maybe unilateral or bilateral solid no cysts no visible cysts hypoplasia of the adjacent normal parenchymal tissue may cause pulmonary hypertension may cause hydrops fetalis type 4 the distal acinar account for 10 to 15 percent of the cases this is the acinar type age range from newborn to five years equally seen in boys and girls lesion involve a single lobe in 80 percent of the cases similar to type 1 both of them are good prognosis/large cysts/present with respiratory distress/cyanosis/large cysts up to 10 centimeters/ thin wall cysts/ lined by smooth membrane/liable to rupture/possibility of pneumothorax