Unusual initial manifestation of metastatic follicular carcinoma of the thyroid with thyrotoxicosis diagnosed by technetium Tc 99m pertechnetate scan: case report and review of literature.
OBJECTIVE
To report a case of metastatic thyroid cancer diagnosed on a technetium Tc 99m pertechnetate (TcO4-) thyroid scan.


METHODS
We present the clinical findings, laboratory results, imaging studies, and surgical pathology report in a man with thyrotoxicosis in whom metastatic well-differentiated thyroid cancer was diagnosed incidentally on a routine TcO4- thyroid scan in the setting of a presumed diagnosis of benign toxic thyroid disease. In addition, we review the literature regarding coexistence of metastatic thyroid cancer and thyrotoxicosis.


RESULTS
A 68-year-old man with thyrotoxicosis was referred for radioiodine therapy. A routine TcO4- thyroid scan revealed high-grade extrathyroidal uptake in the right upper hemithorax as well as in the left side of the thorax. In view of this finding, radioiodine treatment was deferred; further imaging with computed tomography revealed a 6.5-cm mass in a rib on the right side. A biopsy of the rib confirmed the presence of metastatic follicular carcinoma of the thyroid. Scintigraphy revealed sites of metastatic involvement predominantly in the bones along with a cold nodule in the left thyroid lobe, consistent with the primary tumor.


CONCLUSIONS
This case emphasizes the impact of scintigraphic findings on determining the correct management of a patient who would have otherwise undergone inappropriate treatment. Through an extensive literature review, the incidence of malignant involvement in hyperfunctioning thyroid glands and the possible role of sodium iodide symporter expression by thyroid cancer metastatic lesions in preoperative detection of metastatic sites are addressed.
Sundaraiya
Sumati
S
Department of Nuclear Medicine, Royal Sussex County Hospital, Brighton, United Kingdom. s_sumati@yahoo.com
Dizdarevic
Sabina
S
Miles
Kenneth
K
Quin
John
J
Williams
Anthony
A
Wheatley
Trevor
T
Zammitt
Charles
C
D018263:Adenocarcinoma, Follicular / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D000368:Aged; D006801:Humans; D008297:Male; D011859:Radiography; D013670:Sodium Pertechnetate Tc 99m; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D013971:Thyrotoxicosis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology
D013670:Sodium Pertechnetate Tc 99m