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NeoQuest September 2023: A Term Neonate with Persistent Respiratory Distress and Asymmetric Breath Sounds

September 6, 2023

An 8-day-old term neonate has persistent respiratory distress and asymmetric breath sounds with decreased aeration on the left side. Since birth, the infant has required continuous positive airway pressure with an FiO2 of 0.3 and positive end expiratory pressure of 5 cm H2O. Prenatal imaging and birth history were unremarkable. The postnatal evaluation included a normal echocardiogram and abnormal chest imaging (Figure 1).


Figure 1: (A) Chest radiograph obtained in a term infant with persistent respiratory distress and asymmetric breath sounds. (B) and (C): Chest computed tomography obtained in a term infant with persistent respiratory distress and asymmetric breath sounds. Images from: Asif H, Mitchell M, Elmekkawi A, Kukreti V. Persistent work of breathing in a term neonate. Neoreviews. 2023;24(9):e599–e60211

Which of the following is most likely to be associated with this infant’s diagnosis?

  1. Anomalous systemic vascular supply
  2. Male preponderance
  3. Normal tracheobronchial tree
  4. Tumor predisposition syndrome

Explanation:

Answer: B. Male preponderance

This term infant presents with respiratory distress, asymmetric breath sounds, and unilateral overinflation and overexpansion with mediastinal shift on chest radiograph (Figure 1A) and computed tomography (Figure 1B and 1C). These features are consistent with the diagnosis of congenital lobar emphysema (CLE). CLE is a rare lung malformation that can lead to severe respiratory distress in the neonatal and infantile periods. Classically, affected infants present with clinical and radiographic features of air trapping and hyperinflation of one or more lobes of the lung due to partial obstruction of the bronchus (Figure 1). The pathogenesis of CLE can be attributed to the absence of bronchial cartilage, hypoplasia, or dysplasia in 25% of patients.2 However, nearly 50% of CLE cases are classified as idiopathic with no clear etiology.2 CLE occurs in approximately 1/20,000 to 1/30,000 live births and is more common in males than in females, with a 3:1 ratio (Option B).3,4 The left upper lobe is most affected (43%) (as is seen in this patient), followed by the right middle (32%), and then the right upper lobe (21%).5 Severe CLE cases are usually symptomatic and require surgical resection of the affected lobe, which can be curative if there is adequate residual parenchyma.4,6

Other pulmonary malformations can present with respiratory distress in the newborn period. Bronchopulmonary sequestration is a congenital nonfunctioning lung mass that is not connected to the tracheobronchial tree and has an anomalous systemic blood supply (Option A).3,4 The most common subtype that occurs in 75% of patients is the intralobar subtype, which is covered by visceral pleura and embedded within the normal parenchyma of the lung.3 The extralobar subtype has its own separate pleura and is commonly associated with other congenital anomalies such as congenital diaphragmatic hernia. Extralobar bronchopulmonary sequestrations can be located in supradiaphragmatic, intraabdominal, or transdiaphragmatic positions.3 The physical examination of infants with bronchopulmonary sequestration can also reveal respiratory distress and asymmetric breath sounds like infants with CLE, making further workup with imaging necessary to distinguish among possible diagnoses. The imaging of the patient in this vignette does not demonstrate a lobar consolidation, nor does the imaging depict systemic collaterals supplying blood flow to the lesion, which are features that are consistent with a bronchopulmonary sequestration (Figure 2).7


Figure 2: Chest magnetic resonance imaging demonstrating evidence of left-sided lobar consolidation consistent with bronchopulmonary sequestration (star) and its associated systemic supply derived from the aorta (arrow). Image from: Ibrahim J, Sher I, Coren C, Amrita N. Case 1: Secondary structural cause of tachypnea following congenital diaphragmatic hernia repair in a term neonate. Neoreviews. 2016;17(11):e667–e6707

Another abnormality that presents with respiratory distress in the neonate is congenital pulmonary airway malformation (CPAM), formerly known as congenital cystic adenomatoid malformation (CCAM). Comprising approximately 40% of malformations, CPAM is the most common congenital pulmonary abnormality, with an incidence of 1:10,000.4 CPAMs are classified prenatally by the size of the cysts (macrocystic if >5 mm and microcystic if <5 mm) and postnatally by the site of malformation development.3,4 They are most commonly unilobar and usually connect to a normal tracheobronchial tree (Option C).3 CPAM can be confused with a congenital diaphragmatic hernia because of the multicystic—or “bubbly” appearance—on chest radiograph (Figure 3). The physical examination of infants with CPAM, especially if the lesion is large, can present with persistent respiratory distress and asymmetric breath sounds in the same way as CLE. In this case, imaging (Figure 1) is not consistent with CPAM because it demonstrates overinflation and overexpansion of the left lung rather than a multicystic lung lesion.


Figure 3: A. Left upper lobe congenital pulmonary airway malformation (CPAM). (A) Chest radiograph in a neonate exhibiting left-sided upper hyperlucency and multicystic lung lesion, classic radiographic features of CPAM. Pleuropulmonary blastoma can have the same presentation and same imaging findings. (B) Chest computed tomography illustrating a large complex muticystic left-sided pulmonary lesion, confirming the diagnosis of CPAM. Image from: McBride W. Congenital lesions of the lung. Neoreviews. 2016;17(5):e263-e2704

Rarer than CPAM, pleuropulmonary blastoma (PPB) is another congenital lung lesion. Affected infants present with respiratory distress and evidence of a mass or area of consolidation on chest imaging.3 PPB is a type of mesenchymal malignancy of the lung, which may be mistaken for a CPAM based on imaging, as they both can present as a multicystic lesion on chest radiograph and computed tomography.3 However, imaging of patients with PPB does not demonstrate lung overinflation or overexpansion, which were found in the patient in the vignette. If PPB is identified, the diagnosis should raise suspicion for DICER1 syndrome, which places individuals at higher risk for several other malignancies (Option D), necessitating the initiation of a tumor surveillance protocol and multidisciplinary management.8 The DICER1 gene is involved in many biological processes, including lung development and tumorigenesis.9 Individuals with pathogenic variants of the DICER1 gene are at increased risk for several malignancies, including PPB.8,9,10 Because of this increased risk, patients with DICER1 syndrome are screened for an extensive range of associated tumors. The most common associated tumors are typically found in the chest, abdomen, pelvis, and thyroid gland.8 Individuals who develop a malignancy will require additional surveillance.

Did you know?

In 14% to 40% of cases, CLE is associated with other congenital anomalies, most of which are related to the cardiovascular system.11

Which congenital cystic lung abnormalities are thought to be due to altered expression of growth factors?
To find the answer, please read the following article: Flidel-Rimon O, Shinwell ES. Respiratory distress in the term and near-term infant. Neoreviews. 2005;6(6):e289–e29711

NeoQuest September Authors

Allison N. J. Lyle, MD, MA, University of Washington
Neena Jube-Desai, MD, MBA, University of Maryland

References:

  1. Asif H, Mitchell M, Elmekkawi A, Kukreti V. Persistent work of breathing in a term neonate. Neoreviews. 2023;24(9):e599–e602
  2. Demir OF, Hangul M, Kose M. Congenital lobar emphysema: diagnosis and treatment options. Int J Chron Obstruct Pulmon Dis. 2019;14:921–928
  3. King A, Olutoye OO, Lee TC, Keswani SG. Surgical management of congenital lung malformations. Neoreviews. 2023;24(2):e84–e96
  4. McBride W. Congenital lesions of the lung. Neoreviews. 2016;17(5):e263–e270
  5. Moideen I, Nair SG, Cherian A, Roa SG. Congenital lobar emphysema associated with congenital heart disease. J Cardiothorac Vasc Anesth. 2006;20(2):239–241
  6. Vachharajani A, Herco M. A term infant with respiratory distress at birth. Neoreviews. 2019;20(7):e428–e431
  7. Ibrahim J, Sher I, Coren C, Amrita N. Case 1: Secondary structural cause of tachypnea following congenital diaphragmatic hernia repair in a term neonate. Neoreviews. 2016;17(11):e667–e670
  8. Schultz KAP, Williams GM, Kamihara J, et al. DICER1 and associated conditions: identification of at-risk individuals and recommended surveillance strategies. Clin Cancer Res. 2018;24(10):2251–2261
  9. Wagh PK, Gardner MA, Ma X, et al. Cell- and developmental stage-specific Dicer1 ablation in the lung epithelium models cystic pleuropulmonary blastoma. J Pathol. 2015;236(1):41–52
  10. Robertson JC, Jorcyk CL, Oxford JT. DICER1 syndrome: DICER1 mutations in rare cancers. Cancers (Basel). 2018;10(5):143
  11. Flidel-Rimon O, Shinwell ES. Respiratory distress in the term and near-term infant. Neoreviews. 2005;6(6):e289–e297
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