Prevalence and prognostic significance of poor differentiation and tall cell variant in papillary carcinoma in Japan.
BACKGROUND
In the 1980s, histology of a poorly differentiated carcinoma showing an aggressive behavior was proposed by Sakamoto et al. and other pathologists. This was adopted as an independent entity by the World Health Organization (WHO) and in the General Rules for the Description of Thyroid Cancer by The Japanese Society of Thyroid Surgery (JSTS). Furthermore, the Turin classification was recently proposed as the newest classification system for poorly differentiated carcinoma. Furthermore, although tall cell variant is not included in poorly differentiated carcinoma, it is thought to show aggressive characteristics. In this study, we investigated the prevalence and clinical significance of three types of poorly differentiated carcinoma defined by the WHO classification system (poorly differentiated carcinoma [WHO]), Turin proposal (poorly differentiated carcinoma [Turin]), and JSTS (poorly differentiated carcinoma [Sakamoto]), and tall cell variant in papillary carcinoma.


METHODS
We investigated the prevalence and prognostic significance of these three histological types in 1707 papillary carcinomas.


RESULTS
In our series, 189 (11.1%), 15 (0.8%), 5 (0.3%), and 62 (3.6%) patients were diagnosed as having poorly differentiated carcinoma (Sakamoto), poorly differentiated carcinoma (WHO), poorly differentiated carcinoma (Turin), and tall cell variant, respectively. Poorly differentiated carcinoma (WHO) and tall cell variant independently affected cause-specific survival (CSS) of patients, but poorly differentiated carcinoma (Sakamoto) predicted only worse disease-free survival (DFS) of patients on multivariate analysis. Poorly differentiated carcinoma (Turin) showed the worst DFS and CSS rates of patients but was not confirmed as an independent prognostic factor probably because of the small number of patients.


CONCLUSIONS
Poorly differentiated carcinoma (WHO) and tall cell variant significantly affected patient prognosis. Poorly differentiated carcinoma (Turin) accounts only for 0.3% but showed the worst survival rates. Although poorly differentiated carcinoma (Sakamoto) predicted the likelihood of carcinoma recurrence, it is more appropriate to define this lesion as one of the histological subtypes of papillary carcinoma rather than as an independent histological entity.
Ito
Yasuhiro
Y
Department of Surgery, Kuma Hospital, 8-2-35, Shimoyamate-dori, Chuo-ku, Kobe Cit 650-0011, Japan. ito01@kuma-h.or.jp
Hirokawa
Mitsuyoshi
M
Fukushima
Mitsuhiro
M
Inoue
Hiroyuki
H
Yabuta
Tomonori
T
Uruno
Takashi
T
Kihara
Minoru
M
Higashiyama
Takuya
T
Takamura
Yuuki
Y
Miya
Akihiro
A
Kobayashi
Kaoru
K
Matsuzuka
Fumio
F
Miyauchi
Akira
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000453:epidemiology* / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011379:Prognosis; D016019:Survival Analysis; D013964:Thyroid Neoplasms / Q000453:epidemiology* / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy