Clinicopathological significance of a solid component in papillary thyroid carcinoma

Aims Solid variant of papillary thyroid carcinoma ( SVPTC ) is characterized by a solid component ( SC ) involving more than 50% of the tumour with the preservation of the classical cytological features of papillary thyroid carcinoma ( PTC ). However, the clinical significance of SC in PTC has been rarely examined. Herein, we investigated retrospectively the clinicopathological features of PTC with various degrees (10–85%) of SC ( PTCSC ). Methods and results Patients with PTCSC ( n = 27) were stratified into SC ‐major ( SC > 50% of the tumour) and SC ‐minor ( SC < 49%) groups. The clinicopathological parameters were compared to the well‐differentiated PTC ( WPTC ) group ( n = 47). Both SC ‐minor ( n = 18) and SC ‐major ( n = 9) groups had increased incidence of a large‐sized tumour, extracapsular extension and a high recurrence rate, compared to WPTC . Disease‐free survival ( DFS ) of both SC ‐minor and SC ‐major was shorter than that of WPTC ( P = 0.035 and P = 0.016, respectively). Overall survival was similar among all the groups. Univariate analysis revealed that SC was associated significantly with a recurrence rate ( P = 0.018). Using multivariate analysis, SC appeared to be associated with a recurrence rate with borderline significance ( P = 0.055). Conclusions Our findings indicate that the presence of SC in PTC , regardless of the proportion, is associated with adverse clinical parameters and a shorter DFS .