Pneumonitis refers to inflammation of the lung tissue, primarily
affecting the alveoli and interstitial spaces, without necessarily
being caused by an infection. Unlike pneumonia, which is typically
infectious, pneumonitis can result from a variety of non-infectious
causes, including radiation therapy, chemotherapy, inhalation of
toxic substances (like fumes or dust), hypersensitivity reactions (as
seen in hypersensitivity pneumonitis), and certain autoimmune
disorders. The pathogenesis involves an inflammatory response
triggered by exposure to the offending agent, leading to swelling,
fluid accumulation, and sometimes fibrosis in the lung tissue.
Symptoms can include cough, shortness of breath, fever, and
fatigue, and they may vary depending on the severity and underlying
cause. Diagnosis is based on clinical history, imaging (such as
chest X-rays or CT scans showing ground-glass opacities or
interstitial changes), and sometimes lung biopsy to identify the
cause of inflammation.
