Visualization of nasolacrimal drainage system after radioiodine therapy in patients with thyroid cancer

The objective of this study was to report three cases with an accumulation of (131)I in the nasolacrimal duct after radioiodine therapy for papillary thyroid cancer. A whole-body scan was taken 3 days after the administration of 3.7 GBq of (131)I. Single-photon emission computed tomography (SPECT)/CT images were added when the location of a focal tracer uptake was undetermined on whole-body scans. In case 1, a 62-year-old woman complained of epiphora of the left eye after nine radioiodine therapies with a cumulative dose of 31.08 GBq. The left nasolacrimal duct was visualized at her tenth treatment with (131)I. In case 2, a series of three radioiodine therapies had been given to a 73-year-old woman with a cumulative dose of 11.1 GBq. The accumulation of (131)I was noted in the left nasolacrimal duct at her fourth treatment. She complained of epiphora of the left eye. In case 3, bilateral nasolacrimal ducts were visualized at the second radioiodine therapy in a 75-year-old woman. The patient had received 3.7 GBq of (131)I at the first therapy. She did not complain of epiphora. It is possible that radiation from (131)I that is secreted in tears and/or actively accumulated in the nasolacrimal duct may induce nasolacrimal duct obstruction. (131)I in tears would be responsible for the visualization of nasolacrimal duct in the first two cases. (131)I actively accumulated in the nasolacrimal duct might have been visualized in the third case. In summary, (131)I is excreted in tears and is actively accumulated in the nasolacrimal duct. Obstruction of the lacrimal drainage system could occur after high-dose radioiodine therapy.