What is a key clinical feature of miliary tuberculosis as seen on chest radiography?

The key clinical feature of miliary tuberculosis on chest radiography is the presence of millet-like seeding of bacilli throughout the lungs. This typical appearance is characterized by numerous tiny opacities scattered throughout the lung fields, resembling millet seeds. These small nodules represent the widespread dissemination of Mycobacterium tuberculosis via the lymphatic or hematogenous routes, leading to the characteristic miliary pattern.

In contrast, large pleural effusions are associated with other forms of tuberculosis but are not specific to miliary tuberculosis. Mottled opacities may pertain to various pulmonary conditions and are not distinctive for miliary tuberculosis. A single lung nodule would suggest a different pathology, such as a primary lung lesion or a solitary metastasis, which does not fit the diffuse nature of miliary tuberculosis. Thus, the millet-like appearance on chest imaging is what distinctly identifies miliary tuberculosis and helps distinguish it from these other potential findings.