The first reported case of UAPA was published in 1868 and was first demonstrated angiographically in 1952. The true prevalence of this disorder is unknown, but one study suggested that 3 of 600,000 male recruits had chest radiographs suggestive of UAPA. According to one literature review of 108 reported cases of isolated pulmonary artery agenesis without concurrent congenital cardiac disorders between 1978 and 2000, 44% of patients presented with shortness of breath, 37% with recurrent pulmonary infections, and 20% with hemoptysis. The prevalence of PH and heart failure in patients with combined defects can be as high as 88%, although the prevalence of isolated UAPA was only 20 to 25%. The oldest patient in whom UAPA was diagnosed was a 58-year-old woman who presented with a 26-year history of recurrent pleuritic chest pain and pleural effusions. She received a diagnosis on the basis of ventilation-perfusion scan and pulmonary angiography findings. The delay in the diagnosis was due to the nonspecific nature of the presenting symptoms, as was seen in our patient.