Ground glass pulmonary nodules: their significance in oncology patients and the role of computer tomography and 18F–fluorodeoxyglucose positron emission tomography

OBJECTIVE: to determine the clinical significance of ground glass pulmonary nodules, either pure (GGNs) or mixed with the presence of solid component (MPNs), in patients with known pulmonary or extra-thoracic malignancies and to evaluate the role of computed tomography (CT) and positron emission tomography (PET)/CT in their diagnosis and follow-up. METHODS: A total of 130 nodules in 68 patients were revealed: 119 GGNs and 11 MPNs. GGN lesions were found in 58 patients, MPNs in eight, and in two cases, both. The median diameter of the nodules was 7 mm (3–30 mm). Moreover, 27 patients, who had a pars-solid >5 mm in the GGN or a pure GGN with a diameter > 5 mm, underwent FDG PET/CT. The median follow-up with CT was >3 years. RESULTS: The comparison between the first and the last positive CT scan showed that GGNs and/or MPNs remained unchanged for a median period of 18 months (range 11–48 months) in 53 patients, they disappeared after a median of 3.5 months (range 2–11 months) in 12 and increased in diameter after a median period of 17 months (range 12–67 months) in 3. In particular of these latter patients, two had malignant lesions. Only three patients with a single nodule showed a significant uptake of FDG at PET/CT. CONCLUSION: in the evaluation of GGNs and MNPs, CT examinations performed after 3 months often showed some changes, mainly with respect to nodules disappearing. PET/CT often plays no role but it can exclude malignancy at the end of staging. Finally, in patients with known pulmonary or extra-thoracic malignancies showing GGNs or MPNs, a 3-year CT follow up is justified, due to the slow growth rate of these lesions.