Endocrine Abstracts

Introduction: Recent studies have shown that chronic lymphocytic thyroiditis is associated with increased risk of developing papillary thyroid carcinoma (PTC). Although still controversial, these carcinomas appear to have a better prognosis. This study aims to evaluate the presence of thyroiditis in thyroids with PTC and the association with histological variables of prognostic value, Tg and evidence of metastasis in ¹³1I scan.

Methods: Descriptive study of all PTC submitted to thyroid surgery during 24 months (n=192). Information on demographics, histology, Tg at the time of ablative therapy with ¹³1I (¹³1IAT) and fixation in the post-therapy scan (n=116) was obtained. The association between variables was assessed using chi-square tests, multivariate analysis was done using binary logistic regression.

Results: The mean age at diagnosis was 46.9±15.7 years, 82.3% were female patients. Most (77.1%) underwent total thyroidectomy, the average size of the largest tumor focus was 1.4±1.2 cm. The prevalence of thyroiditis was 42.1%. Thyroiditis was significantly more frequent in females (P=0.042), classic variant of the PTC (P=0.002), presence of capsule invasion (P=0.022) and in patients with undetectable Tg (P<0.001). There were no significant associations between thyroiditis and tumor size, encapsulation, presence of necrosis, multifocality, perineural or vascular invasion, extra-thyroid extension, involvement of surgical margins, lymph node metastasis and evidence of distant metastases in ¹³1I scan. Multivariate analysis in the total group of patients showed that only female gender and classic variant of PTC were associated with higher prevalence of thyroiditis, while in the group of patients that underwent ¹³1IAT (in which the variable Tg was included), only absence of detectable Tg and classic variant maintained statistical significance.

Conclusions: Thyroiditis was associated with female gender, classic variant of PTC and absence of detectable Tg, which seems to be in favor of a better PTC prognosis when associated with thyroiditis.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.