The dilemma of 18F-FDG PET/CT thyroid incidentaloma: what we should expect from FNA. A systematic review and meta-analysis

• Published in: Endocrine Vol. 73; no. 3; pp. 540 - 549
• Main Authors: Scappaticcio, Lorenzo, Piccardo, Arnoldo, Treglia, Giorgio, Poller, David N., Trimboli, Pierpaolo
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-09-2021; Springer Nature B.V
• Subjects: Cellular biology; Cytology; Cytopathology; Diabetes; Endocrinology; Humanities and Social Sciences; Internal Medicine; Medicine; Medicine & Public Health; Meta-Analysis; multidisciplinary; Positron emission tomography; Science; Systematic review; Thyroid; Thyroid gland; FNA; Thyroid cancer; Bethesda; F-FDG; PET/CT incidentaloma
• ISSN: 1355-008X; 1559-0100
• DOI: 10.1007/s12020-021-02683-4

Purpose
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F-FDG thyroid incidentaloma (TI) occurs in ~2% of PET/CT examinations with a cancer prevalence of up to 35–40%. Guidelines recommend fine-needle aspiration cytology (FNA) if a focal
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F-FDG TI corresponds to a sonographic nodule >1 cm. The aim of this systematic review and meta-analysis was to provide evidence-based data on the diagnostic distribution of
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F-FDG TIs in the six Bethesda systems for reporting thyroid cytopathology (BETHESDA) subcategories.
Methods
Original studies reporting
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F-FDG TIs and cytologically classified according to BETHESDA were included. Six separate meta-analyses were performed to obtain the pooled prevalence (95% confidence interval, 95% CI) of
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F-FDG TIs in the six BETHESDA subcategories.
Results
Fifteen studies were finally included. Nine studies were from Asian/Eastern and six from Western countries. FNA data according to BETHESDA was available in 2304 cases. The pooled prevalence of
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F-FDG TIs according to BETHESDA was BETHESDA I 10% (6–14), BETHESDA II 45% (37–53), BETHESDA III 8% (3–13), BETHESDA IV 8% (5–12), BETHESDA V 6% (4–9), BETHESDA VI 19% (13–25). A significantly different prevalence was found in the BETHESDA IV between Asian/Eastern (2%) and Western (19%) studies.
Conclusion
Two-thirds of focal
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F-FDG TIs undergoing FNA have either malignant (BETHESDA VI) or benign (BETHESDA II) cytology while a minority will have indeterminate (BETHESDA III or IV) FNA results. Significant differences between Asian/Eastern and Western studies are also present in the prevalence of indeterminate FNA results.