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False-Positive Iodine-131 Uptake Due to Wasp Sting
Address for correspondence: Dr. Nandini Pandit, Department of Nuclear Medicine, Jawaharlal Institute of Post Graduate Medical Education and Research, Puducherry, India. E-mail: drnandinipandit@gmail.com
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Received: ,
Accepted: ,
This article was originally published by Wolters Kluwer - Medknow and was migrated to Scientific Scholar after the change of Publisher.
Abstract
A 38-year-old woman with papillary carcinoma of the thyroid who underwent total thyroidectomy followed by high-dose radioiodine ablation was called for Iodine-131 (I-131) whole-body follow-up scan. Her follow-up scan revealed focal tracer accumulation in the lower aspect of the right posterior neck region. Her stimulated serum thyroglobulin and anti-thyroglobulin antibodies were 0.27 ng/ml and undetectable, respectively. Further clinical examination of the patient revealed a black scab in the same region. The patient revealed a history of wasp bite 2 days before iodine administration.
Keywords
Differentiated thyroid cancer
false positive
Iodine-131 scintigraphy
wasp sting
Radioiodine scintigraphy plays a significant role in the postoperative management of differentiated thyroid cancer.[1] It is important to understand the physiological and nonmalignant pathological Iodine-131 (I-131) distribution sites.[2] False-positive I-131 uptake is not uncommon. Some of the common causes of false-positive I-131 uptake include aortic calcifications, rotator cuff injury, benign bone cysts, vertebral hemangiomas, mature cystic teratomas, ovarian follicle cysts, infectious or inflammatory lung conditions, and subcutaneous injection sites.[34] To the best of our knowledge, there has been only one similar incident of elevated I-131 uptake caused by mosquito bite similar to our case report as depicted in the images [Figures 1 and 2].[5] One possible mechanism of such focal I-131 uptake induced by insect bite could be due to the increased iodine concentration in the inflammatory exudate.[6] This case highlights the significance of a thorough clinical history taking and examination in discerning false-positive I-131 uptake from actual metastatic disease.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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