Adrenocortical adenoma manifesting as false-positive iodine accumulation in a patient with history of thyroid carcinoma

Abstract

A 47-year-old female diagnosed with well-differentiated papillary thyroid carcinoma was referred to our center for a 131Iodine whole body scintigraphy as follow-up. The patient had been previously treated with total thyroidectomy and ablative dose of 175mCi 131I three years ago. Diagnostic 131I scan showed a zone of radioiodine uptake in posterior aspect of the left upper quadrant of the abdomen. Spiral abdominal and pelvic CT scan showed an enhancing solid mass in superior aspect of the left adrenal gland, which was in favor of metastasis to the lymph node or an adrenal tumor. A biopsy was performed from the lesion. Histological examination of the surgical specimen was consistent with adrenocortical adenoma. Even though rare, adrenocortical adenoma should be included in the potential causes of false-positive results of radioiodine scans.

False-Positive 131I Uptake After Posttraumatic Scab in a Patient With Papillary Thyroid Carcinoma

“…Ultrasound of the neck noted no signs of metastatic disease. False-positive 131 I WBS, which can be caused by various etiologies, 1 including anatomic and physiology variants, 2 nonthyroidal pathologic processes, 3,4 and types of issue injury, 5–8 has long been reported. In our case, 131 I uptake in the left knee is more likely related to posttraumatic scab, which has been described in the literature as unusual false-positive finding 9–11 .…”