Radioiodine scan revealing a primary lung adenocarcinoma in a patient with differentiated thyroid carcinoma.

The radioiodine scan is a non-invasive imaging modality that allows for the visualization of functional thyroid tissue, as well as the detection of thyroid cancer remnants and metastases. However, it is important to note that radioiodine uptake is not exclusive to thyroid tissue and can lead to false-positive results if unexpected uptake occurs in non-thyroidal tissue. Herein, we present a case of a patient diagnosed with thyroid carcinoma, whose radioiodine scan demonstrated increased uptake in the thorax, corresponding to a lung carcinoma.