P2.M260: Unraveling Hypogenetic Lung Syndrome with a Bronchogenic Cyst in a 3-Week-Old Infant with Respiratory Distress

Introduction: Hypogenetic lung or Scimitar syndrome (HLS) is a rare congenital condition characterized by partial anomalous pulmonary venous return, hypoplastic right lung, and dextrocardia. In isolation, this syndrome can have benign outcomes, but increased mortality is seen when associated with other cardiac defects and pulmonary hypertension. Bronchogenic cysts are not typically seen with HLS but could potentially cause significant complications.

Case Description: We present a 3-week-old female born prematurely via C-section, with a history of twin-twin transfusion syndrome after in-utero ablation who arrived at the urgent care with a two-day history of cough and congestion. Physical exam was notable for tachypnea and intercostal retractions. She was transferred to the Emergency Department where chest X-ray (CXR) showed patchy opacities consistent with an acute viral illness and superimposed pneumonia versus atelectasis. She subsequently tested positive for Rhinovirus. Given continued respiratory distress, she was admitted to the Pediatric ICU. Respiratory support was escalated to non-invasive ventilation. Follow-up CXR revealed an ovoid lucency at the right, medial basilar lung. Lung ultrasound showed consolidation of the pulmonary parenchyma at the right lung base, concerning for pneumonia. Serial CXRs obtained over the week continued to demonstrate the well-defined ovoid lucency. CT angiogram revealed right lung hypoplasia, partial anomalous pulmonary venous return of all right lung veins into the inferior vena cava (IVC), systemic arterial supply to the right lung from an artery originating at the roof of the celiac axis, and an intra-parenchymal right lower lobe air-filled cyst consistent with a bronchogenic cyst. The patient was diagnosed with HLS and underwent cardiac catheterization with occlusion of the anterior-posterior collaterals, after which pulmonary (Qp) and systemic (Qs) ratio improved from 2.7 to 1.3. The patient was then weaned off respiratory support and was discharged.

Discussion: Bronchogenic cyst in association with Scimitar syndrome is a unique presentation and could cause significant complications such as airway compromise and pulmonary infections. Diagnosis of HLS is often done with the presence of the classic scimitar sign on CXR, however, if the scimitar vein is not visualized, CT angiography or echocardiogram can confirm the diagnosis. Abnormalities within the lung parenchyma such as atelectasis or consolidations may make visualization of a bronchogenic cyst on CXR difficult and thus CT is the imaging modality of choice. The treatment of choice for bronchogenic cysts is surgical intervention, which, in relation to HLS, can compromise pulmonary blood flow intra and postoperatively.

Conclusion: HLS is a rare condition stemming from anomalous pulmonary drainage that can be benign on its own but has increased mortality when associated with other malformations. Even rarer is the finding of a bronchogenic cyst within the same patient. This case demonstrates a unique presentation of the syndrome that could implicate further complications, especially in regard to management.