How do you identify immunotherapy-related pneumonitis vs. radiation pneumonitis in a patient status post chemoradiation receiving consolidation immunotherapy?

Unfortunately, it can be quite difficult to discern the two. Radiation pneumonitis is classically more focal within the treatment field, however, it is absolutely possible to get a more diffuse pneumonitis even with focal RT (albeit uncommon).

https://www.ncbi.nlm.nih.gov/pubmed/15256622

Immunotherapy...