Coexistence of chronic lymphocytic thyroiditis is associated with lower recurrence rates in patients with papillary thyroid carcinoma

Objective  The effect of coexistent chronic lymphocytic thyroiditis (CLT) on prognosis in papillary thyroid carcinoma (PTC) patients remains controversial. We evaluated the influence of coexistent CLT on prognostic outcome and the association of coexistent CLT with clinicopathological parameters.
Design  A retrospective study with a median follow-up of 70 months.
Patients and measurements  Patients with PTC who underwent total thyroidectomy followed by ¹³¹I remnant ablation between 1995 and 2003 at Asan Medical Center, Seoul, Korea were enrolled. CLT was diagnosed histopathologically.
Results  Among 1441 patients, 214 (14·9%) had coexistent CLT. A greater female preponderance was noted in the patients with CLT compared with those without CLT ( P  <   0·01). Mean tumour size in the patients with CLT was smaller than that in patients without CLT (2·0 ± 1·2 vs . 2·2 ± 1·4 cm; P  =   0·02). One hundred and fifty-one (12·3%) patients without CLT had recurrence, whereas 14 (7·1%) patients with CLT had recurrence during the follow-up period ( P  =   0·016). In patients with cervical lymph node metastases, those with coexistent CLT showed a significantly lower recurrence rate than those without CLT ( P  =   0·012). However, this association was lost on multivariate analysis adjusting for other clinicopathological predictors for recurrence.
Conclusions  In this study, CLT was commonly associated with PTC and was associated with smaller size of the primary tumour at presentation. CLT was also associated with a reduced risk of recurrence during follow-up, although this was not significant after adjustment for other prognostic factors.