Vaping-related lung damage in 17 patients resembled chemical burns, U.S. doctors say

Doctors studying lung tissue frompeople with vaping-related injuries have nearly ruled out one diagnosisas a probable explanation of how vaping harms the lungs, but themystery over the exact cause only deepened.

Pathologists from the Mayo Clinic studied lung biopsies from17 patients in the vaping-related outbreak that has sickenedmore than 800 and claimed the lives of 16 people in 13 U.S.states.

In Canada, a Quebec resident has been diagnosed as the country's first case of a severe vaping-related breathing illness.

The U.S. researchers found that none of the cases had evidence of lipoidpneumonia, a rare diagnosis typically associated with peopleaccidentally inhaling oils into their lungs.

In the study published as a letterWednesday in the NewEngland Journal of Medicine, Mayo's Dr. BrandonLarsen and colleagues found no evidence of lipoid pneumonia inany samples they studied.

They suggest that the presence of oilin the lungs may simply be a marker of vaping exposure and notthe cause of vaping-related illnesses.

Their findings differ from early results of astudy of five patients in North Carolina, published on Sept. 6in the Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report.

In those cases, doctors examined lung samples from patientswith severe lung injury and found immune system cells calledmacrophages filled with oil. They diagnosed all five withlipoid pneumonia.

The illnesses have prompted a health scare that has led U.S.officials to urge people to stop vaping, especially productscontaining tetrahydrocannabinol or THC, the marijuana ingredient that produces a high.Several states have also banned some vapingproducts and flavourings in response to theoutbreak.

Chemical irritant

The Mayo Clinic authors said the changes in the lung samples they saw suggest thatthe vaping-related injuries are caused by inhaling chemicalirritants, but the specific agents are not known.

Dr. Jennifer Layden, chief epidemiologist in Illinois, oneof the first states to report vaping-related illnesses, saidlipid-laden macrophages were not a predominant characteristic inthe 53 cases described by Illinois and Wisconsin last month inthe New England Journal of Medicine.

Dr. Laura Crotty Alexander, a pulmonologist who studiesvaping at University of California San Diego, said the Mayofindings are in line with other studies suggesting the injuriesare related to toxic substancesentering the lungs.

"This is just putting further emphasis on the fact thatlipoid pneumonia is not the pathologic pattern being seen inthis epidemic," she said in an email.

Canadian health officials say anyone who has used an e-cigarette or vaping products, and has symptoms such as shortness of breath, cough, chest pain, with or without vomiting, diarrhea, abdominal pain orfever is advised to consult a health-care professional.

People who switched to vaping to cut down on smoking cigarettes should not go back to cigarettes, Canadian health officials said.