The patient, Rameshwar, is undergoing treatment for tuberculosis (TB) at M Y Hospital, where he has been admitted in the ICU.
The 37-year-old suffered burns on his face and neck after the oxygen mask he was wearing suddenly caught fire, a hospital official said.
It was not yet clear what triggered the fire, he said.
When asked about the incident, Hospital Superintendent H D Bhatnagar said he can comment only after getting details of the matter.