Interstitial fibrosis in papillary thyroid microcarcinoma and its association with biological behavior.

Previous studies have revealed that fibrosis may affect the biological behavior of tumors, however associated research on papillary thyroid microcarcinoma (PTMC) is rare. The aim of the present study was to explore the association between interstitial fibrosis (IF) and the biological behavior of PTMC. In the present study, a total of 511 consecutive cases of PTMC were evaluated for the presence of IF and its association with clinical parameters and pathologic biomarkers. IF was identified in 340 of the 511 consecutive cases and it was significantly associated with the age (P=0.033), tumor diameter (P=0.017) and lymphocytic metastasis (P<0.001) of the patient. There were significantly more female in the fibrosis group than in fibrosis-absent group (P=0.024). In the analysis of clinical biomarkers using immunohistochemistical staining, IF was significantly associated with cytokeratin 19 (P=0.008) and galectin-3 (P=0.022). Analysis of patient outcomes indicated that IF was an independent prognostic factor of recurrence (hazard ratio = 2.181; 95% confidence interval = 1.163-4.090; P=0.015). These findings suggest that the combined effect of a patient's age, sex and tumor size may potentially contribute to fibrotic lesions and IF was a factor contributing to poor prognosis in patients with PTMC.