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Significance of what is not sampled: Characteristics of thyroid nonmicrocarcinomas (>1.0 cm) that were not targeted
Author(s) -
Schoedel Karen E.,
Wolfe Jenna,
Hodak Steven P.,
Lebeau Shane O.,
Yip Linwah,
Carty Sally E.,
Nikiforova Mari.,
Nikiforov Yuri E.,
Ohori N. Paul
Publication year - 2015
Publication title -
cancer cytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.29
H-Index - 57
eISSN - 1934-6638
pISSN - 1934-662X
DOI - 10.1002/cncy.21603
Subject(s) - medicine , thyroid carcinoma , thyroid , carcinoma , follicular phase , pathology , thyroid cancer , papillary carcinoma , gastroenterology
BACKGROUND Although most unsuspected thyroid carcinomas qualify as microcarcinomas (≤1 cm), larger, nontargeted carcinomas may be found also. This study evaluated the significance of these nonmicrocarcinomas (>1 cm) in the setting of a large‐volume thyroid practice. METHODS Thyroid resection specimens from May 2007 to December 2012 were reviewed. For these cases, the pathologic characteristics of nontargeted carcinomas larger than 1.0 cm were evaluated. Those interpreted as intrathyroidal metastases were not included in this study. Specifically, the histologic classification, size, and molecular features were documented. RESULTS From a total of 4815 thyroid resections and 9279 thyroid fine‐needle aspiration procedures that were performed during the study period, 27 nontargeted nonmicrocarcinomas were identified (0.6% of resection cases) in 26 patients. The histologic classifications were as follows: follicular variant of papillary carcinoma (n = 19), classic papillary carcinoma (n = 3), papillary carcinoma with oncocytic features (n = 1), tall‐cell variant of papillary carcinoma (n = 2), and follicular carcinoma (n = 2). The size parameters were as follows: mean, 1.9 cm; median, 1.4 cm; and range, 1.1 to 7.0 cm. RAS and BRAF mutations were identified in 8 and 7 cases, respectively (71% of the cases tested with a 7‐gene panel), whereas 6 cases showed no mutation. Molecular information was not available for 6 cases. CONCLUSIONS In the authors' experience, nontargeted thyroid nonmicrocarcinomas (>1 cm) are rare (0.6%), and the majority are low‐grade carcinomas. The likelihood of finding one of the common mutations (71%) is comparable to the likelihood for thyroid carcinomas in general (∼70%). Cancer (Cancer Cytopathol) 2015;123:678–683 . © 2015 American Cancer Society .