Ten percent tall cells confer the aggressive features of the tall cell variant of papillary thyroid carcinoma.
BACKGROUND
The tall cell (TC) variant of papillary thyroid carcinoma (PTC) is more aggressive than classic PTC, but the percentage of TC necessary to diagnose this variant has been debated. We aimed to better determine what percentage of TC correlates with a more aggressive phenotype.


METHODS
Cases from 2005 to 2010 that were the TC variant of PTC or PTC with TC features were identified and compared with classic PTCs. All cases were reviewed to determine what percent, if any, of the tumors consisted of TC.


RESULTS
One hundred forty-one cases of PTC were reviewed. Eighty-three cases had some TC component, and 58 cases had none. There were no differences in patient demographics. Tumors with ≥10% TC had more extrathyroidal extension, angiolymphatic invasion, positive surgical margin, and lymph node involvement than classic PTC. There were more recurrences in patients with ≥10% TC, but this was not significant. Similar findings were also observed with increasing percentages of TC.


CONCLUSIONS
The aggressive features conferred by the presence of TC in PTCs occur with as little as 10% TC and are maintained with increasing percentages. Therefore, TC in a PTC should be reported if they comprise at least 10% of the tumor.
Department of Surgery, Division of Endocrine and Minimally Invasive Surgery, New York Presbyterian Hospital - Weill Cornell Medical College, New York, NY.
Toni
T
Beninato
Theresa
T
Scognamiglio
David A
DA
Kleiman
Alessia
A
Uccelli
Daniela
D
Vaca
Thomas J
TJ
Fahey
Rasa
R
Zarnegar
D000328:Adult; D002277:Carcinoma / Q000473:pathology* / Q000556:secondary / Q000601:surgery; D002291:Carcinoma, Papillary / Q000473:pathology* / Q000556:secondary / Q000601:surgery; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local; D010641:Phenotype; D012189:Retrospective Studies; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000556:secondary / Q000601:surgery