Evolution of the subsolid pulmonary nodule: a retrospective study in patients with different neoplastic diseases in a nonscreening clinical context.

The aims of this study were to evaluate the high-resolution computed tomography (HRCT) features of subsolid pulmonary nodules (SSN) detected in cancer patients to differentiate between benign and malignant lesions, to assess their evolution during the follow-up, and to determine which neoplastic diseases are most frequently associated with the growth in size and/or density of SSN.Ninety-seven patients with a total of 146 subsolid nodules [140 pure ground-glass opacities (pGGOs) and six mixed ground-glass opacities (mGGOs)] were retrospectively recruited. Two chest radiologists independently reviewed the HRCT features of the nodules (location, shape, size, density) and the patients' clinical characteristics (sex, age, smoking and cancer history). Mean duration of follow-up was more than 2 years.During follow-up, 58\% of SSN remained stable, 10\% disappeared. An increase in size and/or density was seen in 32\% of SSN, and in particular in partly solid (mGGOs), large (≥10 mm) and irregular nodules. The majority of small-size (<5 mm) rounded SSN remained stable. SSN growth was more frequent in patients with advanced age and a history of smoking, and occurred even after a long period of stability (39\% of pGGOs "changed" over 3 years). The neoplastic diseases most frequently associated with SSN growth were cancers of lung (34\%), breast (15\%), colon (15\%) and bladder (10\%).The observation of a sample of cancer patients has shown that SSN may frequently grow in size and/or density in these patients, especially if associated powith cancers of lung, breast, colon and bladder. As the majority of SSN showed a very slow development time, a follow-up period longer than 3 years is warranted even in cancer patients.