OBJECTIVES: Recently, the incidence of chronic lymphocytic thyroiditis (CLT) in patients with papillary thyroid carcinoma (PTC) has been increased, yet the effect of CLT on the outcome of PTC remains a matter of debate. The aim of this study was to evaluate the impact of CLT on the outcome of radioactive iodine I-131 remnant ablation (RRA) in patients with PTC.
METHODS: Fifty patients with pathologically proven PTC were retrospectively enrolled in the current study. Patients underwent total or subtotal thyroidectomy, followed by radioactive iodine-123 (I-123) whole-body scan (WBS), neck ultrasound (U/S), serum thyroglobulin (Tg) level and serum Tg antibodies (TgAb) assay. Subsequent RRA was done approximately 6 weeks after thyroid hormone withdrawal. A follow-up radioactive iodine 131 (I-131) WBS, neck U/S, serum Tg, and serum TgAb were performed 6 -12 months later following the suspension of levothyroxine for about one month in 39 cases and following recombinant human TSH (rhTSH) stimulation in 11 cases. TSH-stimulated Tg <1 ng/mL, within normal serum TgAb, negative WBS, and normal U/S were considered the criteria for successful ablation. Patients were categorized into two groups according to the presence or absence of CLT in their histopathology.
RESULTS: Twenty (40%) out of the 50 PTC patients had CLT. No significant difference was found between the 2 groups regarding gender, age, histopathology, the extent of surgery, and ablative dose of I-131. 19/20 patients with evidence of CLT and 23/30 patients without evidence of CLT had negative follow-up I-131 WBS. One patient of those with evidence of CLT and 4 of those without evidence of CLT had a negative follow-up I-131 WBS yet had serum Tg > 5 ng/ml with U/S findings suggestive of residual disease in the neck indicating unsuccessful ablation. The overall successful ablation rate was 90% in group1 compared to 63.3% in group 2 (P< .05).
CONCLUSION: PTC patients with histopathologic evidence of CLT had a higher success rate of RRA and a significantly better outcome as compared to those without evidence of CLT.