Pulmonary metastases in children and young adults with differentiated thyroid cancer.

Background. The prognostic significance and optimal care of children with differentiated thyroid cancer and pulmonary metastases are not well established. Methods. Of 209 patients younger than 25 years of age who were treated at University of Texas M. D. Anderson Cancer Center between 1960 and 1990 and for whom there was sufficient information, 19 (9%) had pulmonary metastases at presentation. Results. All of these patients had regional lymphadenopathy at the time of diagnosis. All but two had intense, diffuse radioiodine uptake in the lungs; there were two false-negative scans immediately after surgical procedure caused by competing thyroid residual. The chest radiograph (CXR) was normal in 8 of 17 (42%) patients with abnormal radioiodine scans. After therapy with radioiodine (100–499 mCi), CXR appeared normal in 7 of 9 patients with initial abnormal radiographs (within 6–75 months). Radioiodine uptake by the lungs normalized in 3 of 8 patients with initially normal radiographs, and in 3 of 9 patients with initially abnormal radiographs. There have been no deaths in these 19 patients. Conclusion. Pulmonary metastases are not uncommon in children and young adults with differentiated thyroid cancer, especially those who have regional lymphadenopathy. The lung metastases almost always concentrate radioiodine diffusely and may be associated with a normal CXR in almost half of the patients. Pulmonary metastases may be overlooked unless near total thyroidectomy is followed by total body radioiodine scan (TBS) in all children and young adults who have regional lymphadenopathy of the neck.