A solid pulmonary nodule is a small, round or oval-shaped lesion in
the lung that appears as a dense, well-defined area on imaging,
particularly chest X-rays or CT scans. These nodules are typically
less than 3 cm in diameter; anything larger is classified as a mass.
Solid pulmonary nodules can be benign or malignant, with common
causes including granulomas (from infections like tuberculosis or
fungal infections), benign tumors (such as hamartomas), and early
stage lung cancer. The pathogenesis varies depending on the cause,
with benign nodules often resulting from localized tissue
overgrowth or healed infection, while malignant nodules arise from
abnormal, uncontrolled cell growth. Diagnosis involves assessing
the size, shape, and characteristics of the nodule on imaging, with
further evaluation such as PET scans, biopsy, or serial imaging to
monitor growth. The risk of malignancy is higher in larger, irregular,
or fast-growing nodules, and accurate assessment helps guide
appropriate management and treatment.