Association between neck ultrasonographic findings and clinico-pathological features in the follicular variant of papillary thyroid carcinoma.
OBJECTIVE
The follicular variant of papillary thyroid carcinoma (FVPTC) has multiple histological subtypes. Clinical outcomes of FVPTC are variable depending on the subtypes. This study evaluated the association of pre-operative ultrasonographic (US) findings and clinico-pathological features of FVPTC.


METHODS
This retrospective study enrolled patients with FVPTC (n = 70), size-matched classical variant of papillary thyroid carcinoma (CPTC, n = 328), follicular carcinoma (n = 85) and follicular adenoma (FA, n = 120). We defined the histological subtypes of FVPTC as infiltrative (I-FVPTC; n = 19) or encapsulated (E-FVPTC; n = 51) according to the presence of a fibrous capsule. Pre-operative US was reviewed using a US scoring system and classified into low US score (n = 42) and high US score (n = 28).


RESULTS
The median US score for FVPTC was lower than CPTC (2 vs 7, P < 0·001), but higher than FA (2 vs 0, P < 0·001). The median US score for I-FVPTC was significantly higher than E-FVPTC (4 vs 2, P = 0·009). I-FVPTC was more likely to be diagnosed as a malignancy or suspicious for malignancy on cytology than E-FVPTC (P = 0·002). The cumulative risks of cervical lymph node (LN) or distant metastasis according to tumour size were significantly higher in I-FVPTC than E-FVPTC (all P < 0·001). The cumulative risks for cervical LN metastasis or capsular invasion according to tumour size were significantly higher in FVPTC with high US score than FVPTC with low US score (P = 0·005, P < 0·001, respectively).


CONCLUSIONS
Pre-operative US findings of thyroid nodules were associated with not only histological subtypes, but also the clinical behaviour in FVPTC.
Department of Internal Medicine, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.
Eun Kyung
EK
Jang
Department of Internal Medicine, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.
Won Gu
WG
Kim
Department of Internal Medicine, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.
Yun Mi
YM
Choi
Department of Internal Medicine, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.
Min Ji
MJ
Jeon
Department of Internal Medicine, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.
Hyemi
H
Kwon
Department of Radiology, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.
Jung Hwan
JH
Baek
Department of Radiology, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.
Jeong Hyun
JH
Lee
Department of Internal Medicine, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.
Tae Yong
TY
Kim
Department of Internal Medicine, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.
Young Kee
YK
Shong
Department of Pathology, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.
Dong Eun
DE
Song
Department of Internal Medicine, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.
Won Bae
WB
Kim
D000328:Adult; D018265:Carcinoma, Papillary, Follicular / Q000000981:diagnostic imaging* / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000473:pathology