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Loyola University Medical Center, Maywood, IL
INTRODUCTION: Unilateral pulmonary artery agenesis (UPAA) is a rare congenital anomaly, which is frequently diagnosed during childhood due to associated cardiovascular abnormalities. Isolated UPAA is even less frequent; usually patients are asymptomatic and are diagnosed during adulthood after an abnormal CXR.
CASE PRESENTATION: A 41-year-old man presented with a 5-day history of worsening shortness of breath associated with chest tightness. He was diagnosed with Mycobacterium avium-intracellulare complex (MAC) pneumonia 2 month prior to this episode and has been treated with antituberculous medications. He has history of chronic bronchitis and was diagnosed with severe asthma as an adult requiring chronic steroids.
Physical exam revealed a comfortable looking man, tachypneic, in no distress. Pulse oximetry revealed 72% oxygen saturation on room air. Chest exam revealed diffuse wheezing and right basilar crackles. The rest of his exam was unremarkable.
CXR revealed a right-sided aortic arch and hyperlucent, contracted left lung. CT of the chest showed an absent left pulmonary artery and ground glass infiltrate in the right base. V/Q scan showed absent perfusion to the entire left lung in the presence of relatively normal ventilation. Echocardiogram did not demonstrate other cardiac anomalies.
DISCUSSION: First review of isolated UPAA cases was published in 1962. Some patients are asymptomatic that can lead to a significant delay in the diagnosis. Recurrent pulmonary infections can be a frequent symptom of isolated UPAA. Pathogenesis is unclear but includes impaired mucociliary clearance and diminished delivery of inflammatory cells due to absent pulmonary perfusion. The result is a relative immunodeficient lung, which is susceptible even to opportunistic pathogens. Refractory wheezing mislabeled, as severe asthma can be an unusual way of presentation as these patients have bronchoconstriction due to alveolar hypocapnea.
Diagnostic possibilities include CXR, echocardiogram along with high resolution CT scan, MRI and V/Q scan. Pulmonary venous wedge angiogram is indicated when revascularization is considered in order to isolate the hilar arteries.
Principal differential diagnosis is Swyer-James or McLeod’s syndrome. Diagnostic imaging of this syndrome include expiratory radiograph with evidence of air trapping and ventilation lung scan showing a delay in the washout phase.
CONCLUSIONS: Isolated UPAA can remain undetected until adulthood. A high index of suspicion coupled with a thorough history, physical examination and a set of imaging tests can lead to a correct diagnosis.
This case illustrates that UPAA should remain in the differential diagnosis of persistent wheezing despite the fact that this is not a usual presentation of the disease.
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