Critical Care: Global Case Report Poster - Miscellaneous |

Isolated Congenital Interruption of the Right Interlobar Pulmonary Artery With Unilateral Fibrotic NSIP-Like Changes of the Lung FREE TO VIEW

Yuki Goto, MD; Kazunori Tobino, MD
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Iizuka, Iizuka, Japan

Copyright 2016, American College of Chest Physicians. All Rights Reserved.

Chest. 2016;150(4_S):275A. doi:10.1016/j.chest.2016.08.288
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SESSION TITLE: Global Case Report Poster - Miscellaneous

SESSION TYPE: Global Case Report Poster

PRESENTED ON: Tuesday, October 25, 2016 at 01:30 PM - 02:30 PM

INTRODUCTION: Isolated congenital interruption of the right interloabr pulmonary artery is a rare disease. There has been only one report to describe the chest CT findings owing to this condition, which showed unilateral idiopathic pulmonary fibrosis (IPF)-like changes. Here, we present the first case of unilateral fibrotic non-specific interstitial pneumonia (NSIP)-like changes due to this condition.

CASE PRESENTATION: A 62-year-old woman was referred to our hospital for suspected recurrent pulmonary thromboembolism (PE). She complained of dry cough and chest pain for two days. Eighteen months before, she was detected abnormal electrocardiographic (ECG) patterns without any symptoms, and diagnosed as PE with CT and perfusion scan. Since then, she had been treated with warfarin, however, her condition and ECG patterns were unchanged. She never smoked. Her oxygen saturation was 94% on room air, and the other vital signs were normal. A physical examination revealed normal breathing and cardiac sounds, and no edema. Laboratory test values were as follows: white blood cells, 5,660/mm3; hemoglobin, 11.6 g/dl; platelets, 115,000/mm3; serum lactate dehydrogenase, 223 U/l; serum aspartate and alanine aminotransferase, 34 U/l and 19 U/l; serum albumin, 2.8 g/dl; serum C-reactive protein, 0.57 mg/dl; serum D-dimer, < 0.5μg/ml; brain natriuretic peptide, 631.2 pg/ml. Serum protein C and protein S activity were normal, and antinuclear antibody, anti-phospholipid antibody, PR3-ANCA and MPO-ANCA assays were negative. An ECG showed nonspecific T-wave abnormalities. Transthoracic echocardiography revealed normal chamber sizes, normal left ventricular function, and no evidence of the other structural heart diseases. Chest radiograph showed reticular changes in the right middle and lower lung field without volume change. 3D-CT with enhancement showed absent right interlobar pulmonary artery without any other abnormalities of pulmonary artery, and also enlarged inferior phrenic artery. HRCT demonstrated ground-glass opacities, reticular changes, and small cysts in the right middle and lower lobes, compatible with fibrotic NSIP. Lung perfusion scan showed total defect in the right middle and lower lobes. The patient was diagnosed as isolated congenital interruption of the right interloabr pulmonary artery, since chronic PE, structural heart disease, systemic congenital disease and systemic vasculitis were ruled out. Her symptoms disappeared on the 2nd day of admission, and her condition continued to be stable without any treatment.

DISCUSSION: To our knowledge, there was only one report about the pulmonary CT findings of isolated congenital interruption of the right interlobar pulmonary artery in English literature (1). It was explained the pathophysiology for this condition may be the partial involution of the proximal sixth aortic arch. The blind end of pulmonary artery at the hilum may cause the anastomoses of pulmonary vessels to systemic arteries. Chest CT findings seen in this condition are thought to represent lung injury (i.e., ischemia, infarction, bleeding and inflammatory change) caused by the pressure gradient between these vessels or high oxygen saturation level. Our patient also had an enlarged inferior phrenic artery distributed to the right lower lobe, however, the pulmonary parenchymal change was thought to be classified as fibrotic NSIP-like changes instead of IPF. The difference of the CT appearance between our patient and the previously reported case was thought to be due to the difference of the grades of lung injury. The most important differential diagnosis is chronic PE, and other differential diagnoses were pulmonary artery involvement of Takayasu’s arteritis or Behçet’s disease (2, 3). Our patient did not have typical findings of these diseases.

CONCLUSIONS: We described the first case of unilateral fibrotic NSIP-like changes due to isolated congenital interruption of the right interlobar pulmonary artery. We believe that our case will add to our understanding and recognition of the spectrum of this rare condition.

Reference #1: Ryu DS, Ahn JH, Choi SJ, et al. Congenital absence of the right interlobar pulmonary artery: HRCT findings. J Thorac Imaging 2008;23:292-294.

Reference #2: Castañer E, Gallardo X, Ballesteros E, et al. CT diagnosis of chronic pulmonary thromboembolism. Radiographics 2009;29:31-50.

Reference #3: Uzun O, Erkan L, Akpolat I, et al. Pulmonary involvement in Behçet's disease. Respiration 2008;75:310-21.

DISCLOSURE: The following authors have nothing to disclose: Yuki Goto, Kazunori Tobino

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