Thyroid cancer is uncommon oncological entity, representing about 1% of all malignant neoplasms. In Egypt, malignant thyroid tumors accounts for 1.48% of total malignant cases. Histological findings may not be sufficient to establish a precise diagnosis for some thyroid lesions and consequently can’t predict their clinical course, common dilemma is encountered with encapsulated tumors exhibiting follicular growth pattern with presence or absence of capsular and/or vascular invasion, aiming to distinguish benign from malignant follicular tumors, another challenging situation is encountered when diagnostic nuclear features of papillary carcinoma are not rising to threshold of classic papillary thyroid carcinoma(PTC). CK19 and High molecular weight CK (HMWCK34BE12) have been used as markers for prognosis in many cancers, but their role in segregating benign thyroid adenomas from atypical nodules and to complete malignant criteria supplied in histopathologically- examined tumors is still unclear.
Aim of the work:
The Purpose of current study is to investigate role of CK19 and HMWCK in separating benign and atypical thyroid nodules from malignant tumors in cases with histopathological criteria not enough to reach accurate diagnosis.
PATIENTS AND METHODS:
This retrospective study was carried upon 70 selected patients with different thyroid lesions including: 12 cases of adenomas (Ad), 9 cases of Atypical nodules (AN), and 49 malignant cases( 22 cases of papillary thyroid carcinoma (PTC), 17 cases of follicular carcinoma (FTC), 5 cases of anaplastic carcinoma (AC) and 5 cases of Medullary carcinoma (MC). Ten cases of non- neoplastic thyroid lesions were taken as control. Materials included formalin-fixed, paraffin-embedded blocks of thyroid lesions received during period from 2005- 2011, where sections were stained with Hematoxylin& Eosin, and immunostained with polyclonal antibodies against CK19 and HMWCK.
RESULTS:
Benign and atypical cases didn’t show diffuse positivity for CK19 in relation to 47% diffuse positivity in malignant cases which was statistically highly significant, p<0.01, statistically significant higher CK19 diffuse positivity was found in follicular carcinoma cases compared to PTC, while CK19 was not expressed in Medullary carcinomas or anaplastic carcinoma variants, p<0.05, cases of PTC expressed HMWCK while cases of FTC, anaplastic carcinomas and Medullary carcinomas did not express HMWCK which was statistically highly significant, p value<0.05.
CONCLUSIONS:
HMWCK and CK19 can be considered as good diagnostic markers for evaluating benign versus malignant thyroid lesions, HMWCK may play an important role to separate benign adenomas from atypical nodules, CK19 can successfully separate atypical encapsulated nodules (completely negative for CK19) from early follicular thyroid carcinomas especially minimally invasive cases( diffusely positive for CK19), and can separate atypical nodules exhibiting incomplete nuclear features supplied for PTC ( completely negative for CK19) from cases with ordinary PTC, HMWCK can confirm diagnosis of follicular variant of PTC and successfully segregating them from follicular thyroid carcinomas, CK19 and HMWCK can separate dedifferentiated thyroid carcinoma with minimal follicular pattern from cases with Medullary and anaplastic carcinomas exhibiting follicular arrangement. Further researches may be mandatory to elicit role of HMWCK and CK19 in prognostic purposes regarding out come in patients with malignant thyroid tumors.
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