The presence of small shadows in the lungs is a morphologic description of the pathology of the lungs by imaging, as detected by X-rays, CT or even MRI of both lungs. Infections of the lungs are most common, including inflammation of the lungs caused by viruses, bacteria, mycoplasma, chlamydia, leptospira, fungi, and Mycobacterium tuberculosis, which cause exudation of inflammatory secretions from the mucous membranes of the lungs, and even hyperplasia and adhesions, resulting in the formation of small, shadowed lesions. It is also seen in chronic diseases of the lung that are caused by non-infectious factors, such as silicosis, pneumoconiosis, and alveolar protein deposition.