Endocrine Abstracts (2009) 20 P157

Bronchiectasis as a false-positive on Iodine-131 scintigraphy in thyroid papillary carcinoma- three case reports

Anabela Martins1, Francisco Rosário1, António Garrão1, Pedro Quaresma2, Teresa Ferreira2, Rita Santos1, Maria Bugalho1 & Valeriano Leite1

1Portuguese Institute of Cancer, Endocrinology, Lisbon, Portugal; 2Portuguese Institute of Cancer, Nuclear Medicine, Lisbon, Portugal.

Introduction: After treatment with Iodine-131(I-131) in differentiated thyroid cancer, a diagnostic scintigraphy is performed. We selected three cases in which bronchiectasis appear as a false-positive on the scintigraphy after treatment with I-131.

Case reports: Three women, respectively 62, 64 and 65 years old, being followed in the Endocrinology Department of our Institute, with the diagnosis of papillary carcinoma of the thyroid, were submitted to I-131 therapy, the last one under recombinant thyroid-stimulating hormone and the others under hypothyroidism.

In all of them, the scintigraphy showed hyperfixation in the lung, consistent with pulmonary metastases. In the first two, the thyroglobulin value was under 0.2 ng/ml and in the last one the value was 1.6 ng/ml; the antithyroglobulin antibodies were undetectable. Chest computed tomography held later did not define nodules considered suspicious, referring to the presence of bronchiectasic lung changes, overlapping with the images of the scintigraphy.

In all these cases the value of thyroglobulin and the title of antithyroglobulin antibodies remained undetectable, with no evidence of recurrence or persistence of disease.

Discussion: In the cases above, the scintigraphy performed after treatment with I-131 showed abnormal fixation in the lung territory, when clinical, biochemical and imagiologycally there was no evidence of recurrence. The presence of bronchiectasis in overlapping locations supports the hypothesis of false-positive in the scintigraphy, already described in the literature.

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