Inflammatory foci in the lungs refer to inflammatory lesions in the lungs, which are found by imaging examinations such as X-ray and CT of both lungs. Infectious foci in the lungs can be caused by infectious factors such as viruses, bacteria, mycoplasma, chlamydia, fungi, protozoa, leptospira, and Mycobacterium tuberculosis, and can manifest after infection as bronchiectasis and lung abscesses. There are also non-infectious lesions, such as idiopathic diffuse interstitial fibrosis of the lung as well as pneumoconiosis and alveolar protein deposition, which can manifest as inflammatory foci in the lung.