Prognostic Significance of the Proportion of Tall Cell Components in Papillary Thyroid Carcinoma.
Tall cell variant (TCV) of papillary thyroid carcinoma (PTC) shows a poorer prognosis than conventional PTC. The World Health Organization (WHO) classification defines TCV as the tall cell component (TCC) in ≥50% of PTC lesions. We investigated whether and how the proportion of TCC affects the prognosis of patients with PTC with TCC.



Seventy patients with TCC in ≥30% of their PTC lesions and 210 age- and gender-matched controls with no TCC who underwent locally curative surgery at Kuma Hospital (2006-2014) were enrolled. The 70 PTC patients were divided into two categories: TCC ≥50% (TCC-major, n = 19) and TCC 30-49% (TCC-minor, n = 51). We performed univariate and multivariate analyses of the relationships between disease-free survival (DFS) and variables including the TCC proportion in 276 patients who had no distant metastases at surgery (median follow-up 64 months).



In the univariate analysis, TCC-major, TCC-minor, old age (≥65 years), clinical node metastasis, significant extrathyroid extension (Ex), and high Ki-67 labeling index (≥5%) significantly affected the DFS. In the multivariate analysis, TCC-major and Ex independently affected the DFS, but TCC-minor did not. In an analysis excluding TCC-major patients, TCC-minor was not an independent prognostic factor for DFS.



Studies or larger patient series with longer follow-ups are necessary, but we speculate that in PTC with TCC, TCC-major significantly and independently affects the DFS, whereas TCC-minor does not. Our findings indicate that the WHO definition of TCV is appropriate and that the prognostic impact of TCC-minor is limited.
Department of Surgery, Kuma Hospital, 8-2-35, Shimoyamate-dori, Chuo-ku, Kobe, 650-0011, Japan. ito01@kuma-h.or.jp.
Yasuhiro
Y
Ito
Department of Pathology, Kuma Hospital, Kobe, Japan.
Mitsuyoshi
M
Hirokawa
Department of Surgery, Kuma Hospital, 8-2-35, Shimoyamate-dori, Chuo-ku, Kobe, 650-0011, Japan.
Akira
A
Miyauchi
Department of Surgery, Kuma Hospital, 8-2-35, Shimoyamate-dori, Chuo-ku, Kobe, 650-0011, Japan.
Takuya
T
Higashiyama
Department of Surgery, Kuma Hospital, 8-2-35, Shimoyamate-dori, Chuo-ku, Kobe, 650-0011, Japan.
Minoru
M
Kihara
Department of Surgery, Kuma Hospital, 8-2-35, Shimoyamate-dori, Chuo-ku, Kobe, 650-0011, Japan.
Akihiro
A
Miya
D000368:Aged; D002291:Carcinoma, Papillary / Q000401:mortality* / Q000473:pathology* / Q000601:surgery; D016022:Case-Control Studies; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D037981:Neck Dissection; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local; D011379:Prognosis; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000401:mortality* / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy