A rare case report of very low thyroglobulin and a negative whole-body scan in a patient with a solid variant of papillary thyroid carcinoma with distant metastases

RATIONALE The early detection of recurrent differentiated thyroid carcinoma (DTC) cells in postsurgery DTC patients relies on the sensitivity of measuring both the level of thyroglobulin (Tg) and 131-iodine distribution on a whole-body scan (WBS). Recent studies have defined patients who subsequently have no evidence of disease as those who have a stimulated Tg level <1 ng/mL with no other radiological or clinical evidence of disease. PATIENT CONCERNS A woman patient with solid variant papillary thyroid carcinoma (SVPTC) had undergone twice thyroidectomy with lymph node dissection and radioactive therapy. Recently, she was found to have lung and brain metastases despite a very low serum Tg level and a negative WBS. Nowadays, the patients have suggested targeted treatment, such as tyrosine kinase inhibitors, may be worthy of consideration to prevent the related events. DIAGNOSES She was diagnosed as PTC. INTERVENTIONS She had undergone twice thyroidectomy with lymph node dissection and radioactive therapy. OUTCOMES She was found to have lung and brain metastases despite a very low serum Tg level and a negative WBS. LESSONS We aim to suggest that patients with SVPTC should be treated cautiously because they may have a higher frequency of distant metastases and a less favorable prognosis compared with patients with classical papillary thyroid cancer.