Histological aggressiveness of fluorodeoxyglucose positron-emission tomogram (FDG-PET)-detected incidental thyroid carcinomas.
BACKGROUND
We previously reported a high incidence of primary thyroid cancer in fluorodeoxyglucose positron-emission tomogram (FDG-PET)-detected incidental thyroid abnormalities. The aim of our study was to determine if these FDG-PET-detected thyroid malignancies represent a more-aggressive variant of primary thyroid carcinoma.


METHODS
All patients that underwent operative intervention for FDG-PET-detected incidental thyroid abnormalities were identified (June 2003 to April 2006). Patients with a diagnosis of primary thyroid carcinoma on final histopathology were included in the study. The patient demographics and histopathological findings were analyzed to identify adverse prognostic features.


RESULTS
In 11,500 patients, 17,250 FDG-PET scans were performed; 377 of these patients (3.2% of patients and 2.1% of FDG-PET scans) had findings positive for thyroid abnormality. Of the 32 patients that underwent operative intervention, 22 patients with a final diagnosis of primary thyroid malignancy were included in the study. A greater number of patients [12 patients, (54%)] were noted to harbor poor prognostic variants of primary thyroid carcinoma on final histopathology [tall-cell variant: 11 patients (50%) and poorly differentiated thyroid carcinoma: 1 patient (4%)]. Extra-thyroidal extension (ETE) was noted in the majority of patients [14 patients (63%)]. In patients with tall cell variant on final histopathology, the rate of ETE was even higher [10 patients (90%)].


CONCLUSIONS
Thyroid malignancies incidentally detected on FDG-PET scan harbor a high rate of unfavorable prognostic features and may represent a more-aggressive variant of primary thyroid carcinoma. These patients need to be subjected to further investigation with a view to possible operative intervention.
Are
Chandrakanth
C
Division of Surgical Oncology, Department of Surgery, Eppley Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA. chandrakanth@hotmail.com
Hsu
John F
JF
Ghossein
Ronald A
RA
Schoder
Heiko
H
Shah
Jatin P
JP
Shaha
Ashok R
AR
D000328:Adult; D000368:Aged; D044963:Biopsy, Fine-Needle; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D033162:Incidental Findings; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18