Subpleural changes (nodules) refer to small, rounded opacities
located near the pleural surface of the lungs, typically seen on high
resolution CT (HRCT) scans. These nodules are found just beneath
the pleura, often in the outermost parts of the lung parenchyma,
and can be associated with a variety of conditions, including
interstitial lung diseases (ILDs), sarcoidosis, metastatic cancer,
asbestosis, and infections like tuberculosis. The pathogenesis
varies; for example, subpleural nodules in ILDs may form due to
chronic inflammation and fibrosis, while in metastatic cancer, they
result from the spread of tumor cells. Diagnosis relies on imaging,
where subpleural nodules are identified based on their size, shape,
and distribution, and additional evaluation with biopsy or PET scans
may be needed to determine their nature.