[Diffuse lung disease: cause of persistent pulmonary hypertension before one year of age].

Pulmonary vascular disease in children is multifactorial and heterogeneous. While it shares some features with pulmonary hypertension in adults, there are differences in the associated comorbidities and conditions, the coexistence of genetic or developmental diseases. Interstitial lung diseases may be responsible for this entity. One is alveolar capillary dysplasia with misalignment of pulmonary veins, a rare pathology but with a mortality rate of 100%, characterized by a failure in the formation of lung tissue that eventually results in impaired gas diffusion. We present a 5-month-old patient studied due to suspected congenital heart disease with persistent hypoxemia; diagnosis was made through lung biopsy.