RESUMEN
Congenital cystic adenomatoid malformation(C.C. A.M.) is a rare variant of congenital pulmonary cystic diseases. C.C.A.M. was first distinguished from other pulmonary cystic lesions by Ch`in and Tang in 1949. It is characterized by cessation of bronchiolar maturation with an overgrowth of mesenchymal elements and proliferation of polypoid glandular tissue in the absence of normal alveolar differentiation. In 80% to 95% of cases, C.C.A.M. of the lung is confinded to a single lobe and there is no lobe predilection and right and left predominance. The clinical presentation may be widely variable, ranging from intrauterine fetal death secondary to nonimmune hydrops fetalis to discovery in childhood after recurrent pulmonary infections. Definitive treatment is removal of affected lobe. In rare instances, there is cases of myxosarcoma, embryonal rhabdomyosarcoma. Bronchoalveolar carcinoma arising in C.C.A.M.. So, resection is recommended even if they are asymtomatic. We have experienced a case of congenital cystic adenomatoid malformation (type II) of the lung in 15 year old man with pneumonia. After the improvement of pneumonia, surgical operation was performed. A brief review of the related literature is presented.