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* From the Department of Medicine (Drs. Davis, Cruz-Gervis, Loyd, and Peebles, and Ms. Marney), Division of Allergy/Pulmonary/Critical Care, the Division of Infectious Diseases (Dr. Tang), and Department of Pathology (Dr. Johnson), Vanderbilt University Medical Center, Nashville, TN.
Correspondence to: Angela M. Davis, MD, Research Fellow, Division of Pulmonary and Critical Care Medicine, Vanderbilt University Medical Center, Nashville, TN 37232-2605; Angela.Davis@mcmail.vanderbilt.edu
The characteristic high-resolution chest CT findings of idiopathic pulmonary fibrosis (IPF)/usual interstitial pneumonitis (UIP) include subpleural arcading, which is a focal wedge-shaped density below the pleural surface and intralobular linear areas of honeycombing. The pathogenic mechanism is unknown, but it suggests an anatomic origin, as in disease of a small airway or vessel. Vasculature changes in patients with IPF were first described in 1963 by Turner-Warwick as subpleural bronchopulmonary anastomoses. However, the etiology is unknown and it is not generally believed to relate to the primary pathogenesis.
In a 46-year-old patient described below, thoracoscopic lung biopsy was performed very early in the course of interstitial lung disease and revealed classic UIP, but in addition the subtotal occlusion of pulmonary arteries due to massive endothelial proliferation was noted. The patients father was a farmer who developed dypsnea on exertion at the age of 56 years. Open-lung biopsy specimen at the age of 61 years in 1973 revealed UIP. Despite treatment with prednisone, he died the following year.
The patients older brother was a railroad clerk who developed dypsnea on exertion at the age of 46 years in 1994. Lung biopsy specimen showed typical UIP, as did the explanted lung at later lung transplant. After unsuccessful treatment with prednisone and cyclophosphamide (Cytoxan), he received a single lung transplant in 1995. He died 31 months after transplantation due to invasive aspergillosis.
Our patient is a 46-year-old farmer who is asymptomatic except for seasonal allergic rhinitis. At his first visit in 1998, he denied symptoms and had normal findings on physical examination and chest radiography, and minimal restriction on pulmonary function testing. High-resolution chest CT scanning showed several bilateral subpleural arcades, some with microscopic honeycombing. During the following year, there was mild progression on CT scan and pulmonary function testing. Lung biopsy specimen showed that 75% of the sample parenchyma was normal, but there were changes typical of UIP, including alternating areas of interstitial fibrosis, inflammation, honeycombing, and normal lung. Airways were normal, but multiple small pulmonary arteries showed extensive proliferation of the endothelium leading to subtotal occlusion. Eosinophils (8 to 10 per vessel) were within the endothelium, and the adjacent vascular media revealed numerous mast cells and a prominent vasa vasorum. Other pertinent laboratory test results included an elevated IgE level (688 ng/dL; normal range, 0 to 99 ng/dL), negative antinuclear antibody, negative rheumatoid factor, negative antineutrophilic cytoplasmic antibody, and the presence of Epstein-Barr virus genome by polymerase chain reaction of lung tissue. Methacholine challenge result was negative. Intradermal allergy skin tests showed moderate-to-severe sensitivities to dust mites, weeds, house dust, and cockroach. We speculate that this new finding of eosinophilic vasculitis may have important implications for the understanding of the pathogenesis of IPF.
Footnotes
Abbreviations: IPF = idiopathic pulmonary fibrosis; UIP = usual interstitial pneumonitis
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