Infants affected with ACD/MPV have progressive respiratory difficulties within the first hours of life and develop respiratory distress and refractory pulmonary hypertension [1, 2]. Although there are reports indicating that more than 90% of the affected newborns are born full term with normal weight and Apgar scores [2], in this case the neonate was a preterm of 29 weeks GA. The clinical presentation also depends on associated congenital malformation because more than 80% of infants may have other malformations affecting the cardiac, gastrointestinal, genitourinary, and musculoskeletal systems.

Within the complementary studies, the chest X-ray films show non-specific signs, such as bilateral opacity or pneumothorax; CT scans show a ground glass image with thickening of the septal line, vascular alterations are not appreciated since the peripheral capillaries of the lung are not visualized. On the other hand, echocardiography allows for confirmation of pulmonary hypertension and rules out structural cardiovascular abnormalities [5]. However, to our knowledge, the usefulness of LU in the follow-up of a patient with ACD/MPV has not been reported before in preterm babies.

Respiratory distress is the most common respiratory neonatal disease. In recent years, LU has been gaining consensus as a safe, non-invasive, bedside, radiation-free tool for the diagnosis and follow-up of several lung conditions in neonatal and pediatric patients [6, 7]. The typical ultrasound findings of SDR are the irregularity of the pleural line with subpleural consolidation and bilateral widespread appearance of “white lung” without spared areas [7]. Many studies have described the usefulness of LU in the diagnosis of RDS and highlight the use of this imaging tool in the assessment and follow-up of a neonate with respiratory distress [7,8,9]. In a recent review, Corsini et al. reported that LU has a sensitivity of 96.7% and a specificity of 100% for the diagnosis of RDS in neonates. Moreover, considering chest X-ray as a gold standard, they found an excellent agreement of 96.7% [6].

However, it should be kept in mind that the combination of LU, chest X-ray, clinical picture and laboratory data must always be integrated to improve the diagnosis of rare conditions of respiratory distress in newborns, such as congenital emphysema, congenital Ureaplasma spp. infection, and some specific pulmonary malformations.

In our preterm neonate, due to the of onset severe respiratory distress within minutes after birth, LU examination was performed. Although LU shows non-specific sonographic signs of ACD/MPV, this non-invasive tool has a crucial advantage, since it allows to assess the severity of respiratory distress, as well as to monitor the progression of lung disease, quantifying changes in lung aeration with high sensitivity.

Nowadays, LU has also been used as a semiquantitative method to monitor the progress of a disease and to decide whether to perform a specific treatment, which was defined by Raimondi et al. as a “functional tool” [9]. Consequently, semiquantitative LU score has been applied in neonatology to predict the need for exogenous surfactant therapy [4, 10,11,12,13]. The predictive accuracy of LU score in neonates was better in preterm infants with GA of less than or equal to 30 weeks, as shown in the area under the curve (AUC) of the ROC curve of 0.94 (95% CI 0.90–0.98). In a recent study, Perri et al. showed that preterm infants with RDS and with LU score ≥ 7 obtained 2 h after exogenous surfactant administration can be useful in identifying patients who will need a second course, showing a sensitivity and specificity of 94% and 60%, respectively [12].

Furthermore, the LU score was shown to predict the need for exogenous surfactant more accurately than the radiological score, with a sensibility of 86% vs. 82%, and a specificity of 88% vs. 76%, respectively [13]. The aim is not to rule out conventional chest X-ray in the management and follow-up of neonates with respiratory distress, but rather to reduce its use and avoid unnecessary exposure to ionizing radiations [8, 9].

The mortality of ACD/MPV is almost 100% within the first month of life, despite using supportive care, including extracorporeal membrane oxygenation [1,2,3, 5]. In our patient, ACD/MPV was suspected due to the lack of response to all established therapy, with severe impairment of lung aeration, as shown by LU (Fig. 1) and chest X-ray (Fig. 2).

A final diagnosis of ACD/MPV is made by pathological examination through lung biopsy or lung tissue autopsy. However, the incidence of the disease is unknown, as many cases pass undiagnosed. Recently, Deng et al. reported a non-invasive method such as DNA sequencing and FOXF1 analysis that could be helpful in the clinical diagnosis of ACD/MPV [14].