Diffuse Sclerosing Variant of Papillary Thyroid Carcinoma Is Associated With Aggressive Histopathological Features and a Poor Outcome: Results of a Large Multicentric Study.

Abstract

Diffuse sclerosing variant (DSV) is a rare and aggressive subtype of papillary thyroid carcinoma (PTC). The objective of the study was to investigate the clinicopathological features and prognosis of DSV patients and compare these findings with all other PTCs and high-risk PTCs. The data of patients who underwent surgery for DSV and PTC between 2003 and 2014 in seven surgical departments specialized in endocrine surgery were reviewed. Fifty-six DSV patients were included (mean age 32.6 ± 12.5 y; 46 [82%] female) and were compared with 2945 non-DSV PTCs and 48 high-risk PTCs. Forty-six DSV patients (82%) were pT3, 43 (77%) had an extrathyroidal extension, and 54 (96%) had lymph node metastasis, including 48 patients with involvement in the lateral compartment (86%). During the follow-up period of 4.3 ±2.3 years, 19 patients (34%) had a recurrence, including 18 patients with an ipsilateral lateral compartment recurrence. The only prognostic factor for recurrence in the multivariate analysis was extranodal extension (odds ratio 3.4 [1.1; 10.8]). The 7-year recurrence-free survival (RFS) was 63%. The RFS was significantly worse in patients with DSV than in other PTC patients (hazard risk 8.5 [5.2; 13.9], P < .0001) and were similar to the RFS of high-risk PTCs (hazard risk 1.1 [0.6; 2.2], P = .5). DSV patients share the same recurrence rate as high-risk PTC patients. Despite aggressive surgical approaches, the recurrence rate within the first 5 years requires a careful ongoing surveillance, similar to the follow-up of high-risk PTC patients.