Atypical presentation and management of a neonate with alveolar capillary dysplasia: A case reportTo the Editor,Alveolar capillary dysplasia with misalignment of capillary veins (ACD/MCV) is a rare interstitial lung disease caused by maldevelopment of alveoli and capillaries. Neonates typically present with intractable pulmonary hypertension within the first 48 hours of life and have a very short life expectancy 1. However, atypical cases have been described with a late, less fulminant clinical presentation and prolonged survival on pulmonary vasodilators, providing a window for bilateral lung transplantation 2.Case presentationOur patient is a female neonate born at 37 weeks of gestation, weighing 3080 gr after an uncomplicated pregnancy. She was admitted to the neonatal intensive care unit (NICU) at the age of two hours due to pneumothorax, which was managed conservatively and absorbed. On the second day of life, she was intubated due to worsening respiratory distress. Over the next several days, unsuccessful extubation trials were attempted. Eventually, she was weaned off oxygen on the 11th day. However, on postnatal day 16, significant respiratory deterioration was noted. Echocardiography revealed moderate pulmonary hypertension, and sildenafil and dopamine were initiated. The patient’s clinical condition and echocardiography findings gradually deteriorated. High-frequency oscillatory ventilation (HFOV) was commenced with a fraction of inspired oxygen (fiO2) up to 1.0. As our patient continued to deteriorate (maximum oxygenation index OI:32 on day 23), we used intravenous iloprost as a pulmonary vasodilator, titrated up to 20 ng/kg/min in combination with levosimendan up to 0.1 mcg/kg/min, to improve cardiac contractility and reduce afterload and pulmonary resistance. Of note, nitric oxide was unavailable in our center at this time. Although gradual improvement in pulmonary hypertension was noticed, our patient developed severe pulmonary edema, which was managed with a continuous intravenous infusion of furosemide titrated up to 0.4mg/kg/h. Intravenous medications were gradually withdrawn, and we could switch to conventional ventilation on the day of life 34. The infant was extubated ten days later.Computed tomography of the lungs showed bilateral symmetrical ground-glass opacification, and genetic testing with whole exome sequencing (WES) revealed a heterozygous missense variant of the FOXF1 gene (c.229T>C;p.Phe77Leu) in exon 1.Our patient remained stable on a high-flow nasal cannula (HFNC) until the 68th day when she was reintubated, and echocardiography revealed severe pulmonary hypertension. On the 72nd day of life, she was transferred to another NICU at the request of her parents. She remained intubated, treatment with pulmonary vasodilators was continued, and finally, a tracheostomy was performed. She eventually died at five months of age. The parents have consent to report the medical details of the neonate.