Poorly differentiated carcinomas of the thyroid with trabecular, insular, and solid patterns: a clinicopathologic study of 183 patients.
BACKGROUND
The term poorly differentiated (PD) carcinoma was proposed 20 years ago to define aggressive, follicular-derived thyroid carcinomas with behavior intermediate between follicular/papillary and anaplastic carcinomas. Among the variable histologic patterns recognized in such tumors, trabecular-insular-solid (TIS) areas usually are predominant. Conversely, some authors pointed out that PD carcinomas are characterized by unequivocal, high-grade histology with atypias, high mitotic counts, and necrosis rather than by a specific growth pattern.


METHODS
The clinicopathologic features of a series of 183 thyroid carcinomas with predominant (n = 165 tumors) or focal (n = 18 tumors) TIS growth patterns were studied by univariate and multivariate overall survival analyses and were compared with clinical outcomes. Subgroups included tumors with predominant oxyphilic features (n = 66 tumors) and (residual) papillary carcinoma features (n = 24 tumors). Control groups of papillary (n = 68 tumors), follicular (n = 71 tumors), and anaplastic (n = 35 tumors) carcinomas also were included for overall survival analysis.


RESULTS
TIS carcinomas had an intermediate behavior between papillary/follicular and anaplastic carcinomas (P < 0.0001). Univariate and multivariate statistical analyses demonstrated that age > 45 years (P = 0.007), the presence of necrosis (P < 0.0001), and a mitotic count > 3 per 10 high-power fields (P = 0.01) were associated with poor outcome. A simplified scoring system based on statistically significant parameters allowed the identification of three prognostic subgroups (P < 0.0001).


CONCLUSIONS
PD TIS carcinomas overall followed a more aggressive course compared with differentiated thyroid carcinomas, irrespective of the extent of the TIS component. However, a numeric scoring system applied to specific clinicopathologic parameters further may identify three prognostic categories of patients who have significantly different survival rates at 5 years and 10 years.
Department of Biomedical Sciences and Oncology, University of Turin, Torino, Italy.
Marco
M
Volante
Stefania
S
Landolfi
Luigi
L
Chiusa
Nicola
N
Palestini
Manuela
M
Motta
Alessandra
A
Codegone
Bruno
B
Torchio
Mauro G
MG
Papotti
D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D002293:Adenocarcinoma, Scirrhous / Q000401:mortality / Q000473:pathology / Q000628:therapy; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001707:Biopsy, Needle; D002277:Carcinoma / Q000401:mortality* / Q000473:pathology* / Q000601:surgery; D002291:Carcinoma, Papillary / Q000401:mortality / Q000473:pathology / Q000601:surgery; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D011336:Probability; D011379:Prognosis; D012189:Retrospective Studies; D012737:Sex Factors; D016019:Survival Analysis; D013964:Thyroid Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy / Q000379:methods; D016896:Treatment Outcome