From the Divisions of *Pulmonary and Critical Care Medicine,
‡Anatomic Pathology, Mayo Clinic College of Medicine and Science, Rochester, MN.
Conflicts of interest and sources of funding: none declared.
Correspondence: Jay H. Ryu, MD, Division of Pulmonary and Critical Care Medicine, Mayo Clinic 200 1st ST, SW, Rochester, MN 55905. E-mail: firstname.lastname@example.org.