1. Department of Pathology and Laboratory Medicine; Hospital of the University of Pennsylvania; Philadelphia; Pennsylvania
2. Department of Pathology; University of Colorado; Denver; Colorado
3. Section of Interventional Pulmonology and Thoracic Oncology; Division of Pulmonary, Allergy, and Critical Care; Hospital of the University of Pennsylvania; Philadelphia; Pennsylvania
4. Department of Pulmonary and Critical Care Medicine; Northwestern Hospital; Chicago; Illinois