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Pathology. 2016 Aug;48(5):425-33. doi: 10.1016/j.pathol.2016.04.002. Epub 2016 Jun 14.

TROP-2 immunohistochemistry: a highly accurate method in the differential diagnosis of papillary thyroid carcinoma.

Author information

1
Department of Pathology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. Electronic address: andrey.bychkov@live.com.
2
Department of Pathology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
3
Department of Pathology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Chulalongkorn GenePRO Center, Research Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.

Abstract

We aimed to evaluate the diagnostic utility of the novel immunohistochemical marker TROP-2 on thyroid specimens (226 tumours and 207 controls). Whole slide immunohistochemistry was performed and scored by automated digital image analysis. Non-neoplastic thyroid, follicular adenomas, follicular carcinomas, and medullary carcinomas were negative for TROP-2 immunostaining. The majority of papillary thyroid carcinoma (PTC) specimens (94/114, 82.5%) were positive for TROP-2; however, the pattern of staining differed significantly between the histopathological variants. All papillary microcarcinomas (mPTC), PTC classic variant (PTC cv), and tall cell variant (PTC tcv) were TROP-2 positive, with mainly diffuse staining. In contrast, less than half of the PTC follicular variant specimens were positive for TROP-2, with only focal immunoreactivity. TROP-2 could identify PTC cv with 98.1% sensitivity and 97.5% specificity. ROC curve analysis found that the presence of >10% of TROP-2 positive cells in a tumour supported a diagnosis of PTC. The study of intratumoural heterogeneity showed that low-volume cytological samples of PTC cv could be adequately assessed by TROP-2 immunostaining. The TROP-2 H-score (intensity multiplied by proportion) was significantly associated with PTC variant and capsular invasion in encapsulated PTC follicular variant (p<0.001). None of the baseline (age, gender) and clinical (tumour size, nodal disease, stage) parameters were correlated with TROP-2 expression. In conclusion, TROP-2 membranous staining is a very sensitive and specific marker for PTC cv, PTC tcv, and mPTC, with high overall specificity for PTC.

KEYWORDS:

TROP-2; automated image analysis; differential diagnosis; immunohistochemistry; papillary thyroid carcinoma; thyroid

PMID:
27311870
DOI:
10.1016/j.pathol.2016.04.002
[Indexed for MEDLINE]

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