ACHALASIA: A CAUSE OF FALSE POSITIVE MEDIASTINAL 131I UPTAKE IN A PATIENT WITH THYROID CANCER

Abstract

Unusual features of ¹³¹I uptake during thyroid cancer scintigraphy may lead to a false-positive diagnosis of residual or recurrent malignancy and associated metastasis. A proper understanding of the causes of falsepositive ¹³¹I scans is essential for accurate interpretationof the images and to obviate diagnostic errors which may leadto administration of unnecessary therapy doses. We are reporting a case of a 55-years old man with history of total thyroidectomy for papillary thyroid cancer, followed by ablation therapy with 100 mCi of ¹³¹I for residual thyroid disease. A follow-up scan obtained after one year showed a large area of ¹³¹I uptake in mediastinum, which was subsequently found to be due to accumulationof radioiodine in a grossly dilated esophagus secondary toachalasia. Â For the accurate interpretation of ¹³¹I whole-body scans, awareness of potential causes of false positive findings is important to ovoid unnecessary radiation burden to the patients.