open access

Vol 69, No 6 (2018)
Case report
Published online: 2018-10-11
Submitted: 2018-03-09
Accepted: 2018-04-22
Get Citation

False-positive radioiodine whole-body scan due to a renal cyst

Adam Maciejewski, Rafał Czepczyński, Marek Ruchała
DOI: 10.5603/EP.a2018.0071
·
Pubmed: 30306537
·
Endokrynologia Polska 2018;69(6):736-739.

open access

Vol 69, No 6 (2018)
Case report
Published online: 2018-10-11
Submitted: 2018-03-09
Accepted: 2018-04-22

Abstract

Patients affected by differentiated thyroid cancer are treated surgically and by ablative radioiodine therapy. A post-therapy whole-body scan allows detection of thyroid remnants or local and distant metastases, although false-positive findings may be observed. We report a case of a 75-year-old woman with follicular thyroid cancer, who underwent ablative radioiodine treatment. On post-therapy wholebody scan, abnormal uptake in the left upper abdomen was found, although stimulated thyroglobulin level was not suggestive for distant metastases of differentiated thyroid carcinoma. Additional SPECT/CT acquisition revealed focal 131I uptake located at the posterolateral wall of the left kidney corresponding to a round lesion 47 mm in maximal diameter. In order to verify this finding abdominal ultrasound and abdominal contrast-enhanced CT were performed, confirming multiple renal cysts in the left kidney; the largest one was the site of abnormal radioiodine accumulation. Despite the high incidence of renal cysts, especially in the elderly, radioiodine uptake in renal cysts
is extremely rare. Different hypotheses on the mechanism of radioiodine uptake in the cyst were proposed, among them active secretion by sodium-iodide symporter or other transporting proteins. We conclude that abnormal radioiodine uptake in renal cysts can be an exceptional finding mimicking a metastasis.

Abstract

Patients affected by differentiated thyroid cancer are treated surgically and by ablative radioiodine therapy. A post-therapy whole-body scan allows detection of thyroid remnants or local and distant metastases, although false-positive findings may be observed. We report a case of a 75-year-old woman with follicular thyroid cancer, who underwent ablative radioiodine treatment. On post-therapy wholebody scan, abnormal uptake in the left upper abdomen was found, although stimulated thyroglobulin level was not suggestive for distant metastases of differentiated thyroid carcinoma. Additional SPECT/CT acquisition revealed focal 131I uptake located at the posterolateral wall of the left kidney corresponding to a round lesion 47 mm in maximal diameter. In order to verify this finding abdominal ultrasound and abdominal contrast-enhanced CT were performed, confirming multiple renal cysts in the left kidney; the largest one was the site of abnormal radioiodine accumulation. Despite the high incidence of renal cysts, especially in the elderly, radioiodine uptake in renal cysts
is extremely rare. Different hypotheses on the mechanism of radioiodine uptake in the cyst were proposed, among them active secretion by sodium-iodide symporter or other transporting proteins. We conclude that abnormal radioiodine uptake in renal cysts can be an exceptional finding mimicking a metastasis.

Get Citation

Keywords

follicular thyroid cancer; renal cyst; radioiodine; post-therapy whole-body scan

About this article
Title

False-positive radioiodine whole-body scan due to a renal cyst

Journal

Endokrynologia Polska

Issue

Vol 69, No 6 (2018)

Pages

736-739

Published online

2018-10-11

DOI

10.5603/EP.a2018.0071

Pubmed

30306537

Bibliographic record

Endokrynologia Polska 2018;69(6):736-739.

Keywords

follicular thyroid cancer
renal cyst
radioiodine
post-therapy whole-body scan

Authors

Adam Maciejewski
Rafał Czepczyński
Marek Ruchała

References (15)
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