Spontaneous regression of intralobar pulmonary sequestration during the pregnancy: report of two cases through relationships between mass and fetal biometry and review of the literature.

Intralobar pulmonary sequestration is a rare bronchopulmonary malformation consisting of a non-functioning lung mass that receives its arterial blood supply from systemic circulation and that does not adequately communicate with the tracheobronchial tree through a normal bronchus. These sequestrations account for 1.1-1.8% of all lung resections. Herein we present two clinical cases with a prenatal diagnosis of pulmonary sequestration using ultrasound and magnetic resonance imaging. Pulmonary images indicated a progressive decrease in the size and echogenicity of the lung mass with fetal growth, resulting in asymptomatic neonates with normal chest radiographs. We emphasize the importance of combining imaging examinations with follow-up by a multidisciplinary team working in a center specialized in maternal-fetal medicine. For the successive monitoring of the size of the lung tissue mass, we propose the calculation of the following two biometric ratios that are not yet described in the literature: mass area/head circumference and mass volume/estimated fetal weight. The second ratio was similar in both cases, a result which suggests its potential for use in estimating the probability of the spontaneous regression of intralobar pulmonary sequestration.