Cerebral metastases from thyroid carcinoma: complete remission following radioiodine treatment.

BACKGROUND

Brain metastases arise in roughly 0.9% of all cases of differentiated thyroid cancer. The median survival of adult patients with thyroid carcinoma that has metastasized to the brain is less than one year. Radioactive iodine treatment is only rarely given because its efficacy is not documented. In children, the situation may be different.

METHOD

In 2005, a 15-year-old girl underwent thyroidectomy, and an oxyphilic variant of papillary thyroid carcinoma was found in ectopic thyroid tissue. The patient underwent oral, high-dose radioactive iodine treatment. The post-therapeutic I-131 whole-body scan revealed multiple metastases in the skeleton, lungs, and the soft tissues, along with physiological uptake of the residual thyroid tissue. Magnetic resonance imaging of the head revealed two brain metastases.

RESULTS

When the initial treatment was completed, additional age-adapted high-dose radioactive iodine treatment was given, up to a total activity level of 35 GBq. There followed a complete remission of all metastases in the brain, bones, lungs, and soft tissues. Computed tomography of the chest revealed stable residuals. Over the ensuing 7.5 years of follow-up, the thyroglobulin values steadily declined to less than 2 ng/mL. The patient was asymptomatic at her last follow-up in May 2013. She did not develop any delayed reaction to high-dose radioactive iodine treatment (in particular, she did not develop leukemia or any other secondary malignancy). She remained fertile: after completion of the treatment, she had two healthy children.

CONCLUSION

In this patient with multifocal thyroid carcinoma, a rare entity, radioactive iodine treatment was successful as the single treatment. This case illustrates the point that a given therapeutic modality might succeed in an individual case despite a total or near-total lack of efficacy for most patients in the same situation.