Congenital pulmonary airway malformation or CPAM is a rare anomaly which affects specifically one and usually lower lung lobe. In most cases it is detected during prenatal life with foetal ultrasound, but it`s not uncommon to find CPAM in background of frequent respiratory infections in childhood, rarely even in adulthood. In this paper, our aim is to present an atypical presentation of CPAM type I which we had difficulties to diagnose. Our case shows CPAM as a substrate for development of tension pneumothorax in 5-months old infant facilitated by acute bronchitis. After initial thoracic drainage and regression of pneumothorax a recurrent pneumothorax was developed and consequently CPAM was suspected. Following CT scans showed CPAM lesion in lower right lung lobe with mediastinal shift and consolidation of adjacent lung tissue. Parenchyma sparring lung resection was done and histological analysis verified CPAM type I lesion. No postoperative complications occurred and infant`s further development was normal during regular follow-up.