Table 8.
Patient and Lesion Characteristics of Cases with Discordant Molecular Diagnostics and [18F]FDG-PET/CT Results
| Casea | Age (years) | Sex (M/F) | US size (mm) | Cytology | [18F]FDG avid | SUVmax (g/cm3) | MD result | Histopathological diagnosis |
|---|---|---|---|---|---|---|---|---|
| [18F]FDG−/MD+, malignant or borderline histopathology | ||||||||
| 1 | 65 | F | 15 | FN | No | 2.5 | NRAS (c.182A>G) | PTC, spindle cell variant, 15 mm, pT1bb |
| 2 | 47 | F | 35 | AUS | No | 2.2 | ETV6/NTRK3 fusion | FVPTC, 32 mm, pT2N0M0c |
| [18F]FDG−/MD+, benign | ||||||||
| 3 | 62 | M | 36 | AUS | No | 0.7 | EGFR (c.2270A>G) | FA, 25 mm |
| 4 | 41 | F | 10 | FN | No | 2.0 | DICER1 (c.5126A>G) | FA, 12 mm |
| 5 | 50 | F | 36 | AUS | No | 2.5 | PTEN (c.755_758delATAT) | FA, 25 mm |
| 6 | 61 | F | 43 | AUS | No | 2.6 | TERT (c.-124C>T) | FA, 36 mm |
| 7 | 34 | F | 47 | AUS | No | 2.1 | DICER1 (c.5126A>G) | No surgery, unchanged after 37 months f/u |
| 8 | 74 | M | 53 | AUS | No | 3.2 | PTEN (c.379G>A) | No surgery, unchanged after 45 months f/u |
| 9 | 63 | F | 46 | AUS | No | 3.5 | CDKN2A (c.167G>T) | No surgery, unchanged after 50 months f/u |
| [18F]FDG+/MD−, malignant or borderline histopathology | ||||||||
| 10 | 58 | F | 15 | FN | Yes | 2.1 | NIFTP, 20 mm | |
| 11 | 75 | F | 24 | AUS | Yes | 12.2 | RCI type CNA | FT-UMP with oncocytic changes, 21 mm |
| 12 | 50 | F | 41 | FN | Yes | 5.9 | Paraganglioma, 40 mm | |
| 13 | 52 | F | 29 | AUS | Yes | 3.4 | PTC, 8 mm, pT1aN0M0 | |
| 14 | 46 | F | 36 | FN | Yes | 3.9 | FTC, 37 mm, pT2N0M0 | |
Case numbers correspond to case numbers in Supplementary Table S2.
This 15-mm neoplasm was difficult to diagnose, with a differential diagnosis of PTC or FA. After review by multiple expert thyroid pathologists and MD, it was finally considered a PTC, spindle cell variant, pT1b.
This was a 32-mm follicular neoplasm with an 8-mm solid component and large cystic component, with a differential diagnosis of follicular adenoma or FVPTC. Morphologically difficult to diagnose, it was considered a pT2N0 M0 FVPTC only after an ETV6/NTRK3 fusion was found on additional MD performed during revision of the histopathology. Both [18F]FDG-PET false-negative cases were previously discussed in more detail.18
CNA, copy number alterations; F, female; FA, follicular adenoma; M, male; RCI type, reciprocal chromosomal imbalance; US, ultrasound.