Proportion and characteristics of transient nodules in a retrospective analysis of pulmonary nodules.

Abstract

Pulmonary nodules manifest as pure or mixed ground glass opacities (GGOs), or solid nodules. We retrospectively surveyed 317 cases with pulmonary nodules to observe the proportion and predictive factors of transient lesions in patients with pulmonary nodules. At the initial computed tomography scan, 63.7% showed solid nodules, while 20.2% had mixed GGOs and 16.1% of cases manifested as pure GGOs. Nodules from 114 cases (36%) disappeared or decreased in size during follow up, while in 203 cases (64%), they did not change or became enlarged. During follow up, more than half of the GGOs resolved (66.7% in pure GGOs, 54.7% in mixed GGOs), while only 22.3% of solid nodules resolved. Between transient and persistent pulmonary nodules, significant differences were observed in age, gender, smoking history, presence of eosinophilia, size, and radiologic attenuation of nodules (solid or GGO). In multivariate analysis, age (≤55 years), size of nodules (>15 mm), eosinophilia, and GGO were significant independent predictors of transient nodules. The main causes of transient nodules were pneumonia or eosinophilic pulmonary infiltrates. Thirty-six percent of pulmonary nodules resolved spontaneously or with medical treatment. Transient nodules showed different clinical and radiological characteristics from persistent nodules.