Appearance of antithyroglobulin antibodies as the sole sign of metastatic lymph nodes in a patient operated on for papillary thyroid cancer: A case report

We report a case in which the appearance of a progressively rising titer of thyroglobulin (Tg) antibodies was the most sensitive marker of papillary t hyroid cancer relapse at loco-regional lymph nodes. The patient, a 60-year- old man, had been treated with total thyroidectomy plus lymphadenectomy and radioiodine ablation for a 1-cm papillary thyroid cancer. Twelve years aft er surgery, while undergoing levothyroxine (LT4) therapy, Tg antibodies wer e first detected and progressively rose from 99 to 1,697 U/mL in 18 months, while serum Tg remained undetectable. Both neck ultrasonography and I-131 whole-body scan (WBS) were unremarkable. Enlarged lymph nodes became palpab le at the left laterocervical region only 2 years after the first appearanc e of Tg antibodies and were surgically removed after cancer relapse was con firmed by fine-needle aspiration cytology. This case emphasizes the possibi lity that in thyroid cancer patients who have undergone total thyroidectomy , the appearance of Tg antibodies may indicate metastatic lymph nodes even when serum Tg is undetectable and WBS negative.