Expression of cytokeratin-19 (CK19) in the classical subtype of papillary thyroid carcinoma: the experience of one center in the Silesian region.

INTRODUCTION Cytokeratin-19 (CK19) is recognized as a reliable tumor marker of papillary thyroid carcinoma (PTC). The general prognosis in the classical subtype of PTC (CSTPTC) remains favorable, but some cases can be very aggressive. The aim of this study was to evaluate the localization and intensity of immunohistochemical CK19 expression in CSTPTC and its associations with the clinical and pathological characteristics of patients with CSTPTC in the Silesian region. MATERIAL AND METHODS All the available clinical and histopathological data for 149 patients with CSTPTC from the Silesian region were retrospectively analyzed. The group consisted of 135 (90.6%) women and 14 (9.4%) men (mean age and SD: 52.3 ± 15.0). All these patients with CSTPTC underwent surgery at the same center between 2008 and 2013; the follow-up period was 24 to 90 months (mean and SD: 47 ± 20). RESULTS In 142 (95.3%) of the patients with CSTPTC, positive cytoplasmic staining of CK19 was found. A higher expression of CK19 was observed in the group of patients without the recurrence of the disease (p = 0.015). CK19 expression was not associated with age, gender, tumor focality, disease stage, tumor size (pT), lymph node involvement (pN), or distant metastases (pM). CONCLUSIONS Decreased CK19 expression in CSTPTC cases with relapse suggests that it plays a role in the carcinoma progression of CSTPTC. The association between lower CK19 expression and patients' unfavorable postoperative course could suggest its possible role as a marker of CSTPTC poor prognosis.