Peer Reviewed
What Is the Cause of This Infant’s Alveolar Infiltrates?
AUTHORS:
Jennifer Bouso, MD, MSPH, and Okan Elidemir, MD
CITATION:
Bouso J, Elidemir O. What is the cause of this infant’s alveolar infiltrates? Consultant. 2016;56(11):1004-1007.
A 6-month-old girl with a history of an H-type tracheoesophageal fistula (TEF) repaired at 2 weeks of age presented to the pediatrician’s office. The girl had a 1-week history of cough and rhinorrhea, and the cough was not associated with feeding, position, hemoptysis, or sputum production.
On physical examination, the infant was afebrile with normal vital signs and oxygen saturation over 95% on room air. She was well appearing and slightly tachypnic, but not in any respiratory distress, with unremarkable lung examination on auscultation and a respiratory rate of 56 breaths/min. A chest radiograph obtained in the pediatrician’s office was significant for alveolar infiltrates (Figures 1 and 2), and the patient was referred to a pediatric pulmonologist.
What is the cause of the alveolar infiltrates?
Answer and discussion is on the next page.
Answer: Barium aspiration
The chest radiograph results suggested disease in the alveolar space evidenced by alveolar infiltrates. Substances that may accumulate in the alveolar space include surfactant, calcium, hemosiderin, and radiopaque substances such as barium.
The diagnosis for our patient became evident after reviewing her previous hospitalization history. She initially presented in the first 2 weeks of life with failure to thrive and feeding intolerance. A barium swallow was done at that time, which resulted in barium aspiration and chemical pneumonitis requiring intensive care. A chest radiograph that immediately followed the aspiration is shown in Figure 3. Later, a more specific contrast study revealed the H-type fistula. Over the following 2 weeks, the patient recovered from her pneumonitis and subsequently underwent a successful TEF repair.
A radiograph ordered by the pediatrician when the girl presented at age 6 months (Figures 1 and 2) shows residual barium from the initial insult and is actually improved from the films immediately post-aspiration (Figure 3).
DIFFERENTIAL DIAGNOSIS
Barium aspiration should be considered if the patient’s history includes a barium study, even if it was not done recently. Barium is an inert chemical with high molecular weight that gives dramatic evidence of its presence on radiograph and yet is generally benign when introduced to the respiratory system.1 When a small amount of barium is aspirated in the tracheobronchial tree, it is rapidly cleared by coughing or removed by mucociliary clearance. However, if a significant amount of barium is aspirated, it may be retained in the interstitium or phagocytized by macrophages leading to prolonged retention for months to years.1
If thorough history-taking does not divulge the diagnosis in a patient with alveolar infiltrates on chest radiograph, the next best step in evaluation would be referral to a pediatric pulmonologist for high-resolution computed tomography and bronchoscopy with bronchioalveolar lavage.
Another possibility to consider is pulmonary alveolar proteinosis (PAP), which is a problem with surfactant homeostasis and is characterized by the accumulation of lipoproteinaceous material in the alveoli and inside alveolar macrophages.2 The major defect in this disease is the inability of the macrophages to be activated by the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF).3 Without appropriate stimulation by GM-CSF, macrophages internalize but do not catabolize surfactant.3 PAP may be the result of a genetic defect, an acquired autoimmune disease, or the result of a toxic exposure such as chemotherapy.2 Presentation of PAP is variable and can present as respiratory failure in infancy or as slowly progressive dyspnea depending on the underlying defect.2,3 Bronchioalveolar lavage in these patients reveals a milky, brown fluid that is positive on periodic acid–Schiff staining with foamy, surfactant-laden alveolar macrophages.2,3
The differential diagnosis should also include pulmonary alveolar microlithiasis (PAM), a rare autosomal recessive mutation affecting the alveolar phosphate cotransporter.4 When this transporter is defective, phosphate builds up in the alveolar space, yielding microliths.4 Although the classic presentation of PAM is an abnormal chest radiograph in an asymptomatic patient, the natural history of this disease is progressive, end-stage lung disease.4 Bronchioalveolar lavage or biopsy can confirm the diagnosis by revealing the calcified spherules.4
In addition, diffuse alveolar hemorrhage (DAH) is a potential diagnosis. DAH can be caused by a large group of diseases in which there is capillary hemorrhage into the alveolar space.5 It is typically caused by an immune-mediated process of vasculitis or capillaritis, such as Goodpasture syndrome, but it also may be the result of a nonimmune process, a toxin, a drug-mediated reaction, or an idiopathic process (idiopathic pulmonary hemosiderosis).5,6 DAH is evidenced by hemosiderin-laden macrophages in bronchoalveolar lavage fluid.5 Consideration of infectious causes of diffuse alveolar infiltrates, such as Pneumocystis jirovecii, may be necessary if suggested by the patient’s history or immune status.
DISCUSSION
Barium provides us with a seemingly ideal modality of evaluating the swallowing mechanism, but there have been cases of serious pathology, even death, secondary to massive barium aspiration.7,8 Pathophysiology of these severe consequences is likely 2-fold, secondary to both mechanical obstruction leading to alveolar dead space and an acute inflammatory reaction related to the aspiration of erosive gastric contents in addition to barium.9 Despite this risk, adverse events are extremely rare, and barium contrast studies should not be avoided because of this potential complication.1 Long-term complications of retained barium in the alveolar space after aspiration are somewhat controversial. Voloudaki and colleagues reported the presence of interstitial fibrosis in an adult patient 1 year after barium aspiration.9 However, contrast bronchography was commonly used in the past without consequence, and baritosis is widely accepted as a benign pneumoconiosis that self-resolves in time once the exposure to barium is removed.10,11
CONCLUSION
Barium aspiration is typically a benign complication of barium contrast diagnostic evaluation. In rare cases, there can be severe, life-threatening chemical pneumonitis if the aspiration is large. Alveolarized barium can persist for months to years and will be visualized on radiograph as diffuse alveolar opacities.
Our patient recovered easily from her viral upper respiratory infection. The aspirated barium currently is not causing our patient any significant disease, and she continues to be asymptomatic. The plan is to monitor her with serial imaging every 6 months for resolution of the alveolarized barium.
Jennifer Bouso, MD, MSPH, and Okan Elidemir, MD, are from the University of Florida School of Medicine, Department of Pediatrics, and the Nemours Children’s Subspecialty Clinics, Department of Pediatric Pulmonology, both in Pensacola, Florida.
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