Congenital cystic adenomatoid malformation (MAKC) is a congenital anomaly of lung development, and is defined as an adenomatoid proliferation of terminal respiratory structures, bronchial and distal pulmonary cystic dilatation, communicating with the bronchial tree and lacking cartilaginous rings, representing approximately 25% of congenital lung lesions, and in 80 to 85% of cases, the diagnosis is made before the age of 2 and is rarely discovered in adulthood. We report 01 case of MAKC diagnosed at the age of 06 months. The diagnosis was based on clinical elements (episode of bronchiolitis with serious signs at the age of 5 months) and radiological (TLT and CT). The lesion was located in the lower lobe of the right lung. The patient underwent a surgical resection such as a lower right lobectomy removing the lesion in one piece. The discovery of a MAKC must be recognized by clinicians. The clinical diagnosis, strongly oriented by the radiological approach, is confirmed by the anatomical pathology, the therapeutic sanction is surgical in the majority of cases. Most authors indicate surgery, especially in early childhood in order to avoid complications, mainly recurrent infections and pneumothorax, and to take advantage of the potential for lung growth.