Metastatic papillary thyroid carcinoma with no primary tumor in the thyroid gland: a case report and review of literature

Metastatic papillary thyroid carcinoma in the lymph nodes with no primary tumor in the thyroid gland is rarely reported and is easily missed. We report the case of a 27-year-old female who presented with a tiny nodule in her left thyroid gland, which was detected during a routine ultrasonographic examination. She did not present with fever, weight loss, or night sweats, and no palpable mass was found in the physical examination. The preoperative blood routine, thyroid function, and thyroglobulin test results were normal. Needle aspiration cytology of the thyroid and lymph nodes was recommended. However, the patient was anxious and refused to have a fine-needle aspiration biopsy (FNAB), requesting surgical excision instead. The patient underwent a left thyroid lobectomy and ipsilateral central lymph node dissection under general anesthesia. Metastasis of papillary thyroid carcinoma was found in the central lymph nodes although there was no primary tumor in the left thyroid gland. We reviewed the literature and found the possible hypotheses to explain this phenomenon included the lack of a pathologic biopsy, tumor regression, and ectopic thyroid carcinoma. After 2 years of follow-up, no recurrence or metastasis of the tumor was found in this patient. In conclusion, we believe attention should be paid to occult thyroid cancer with papillary carcinoma in the lymph nodes so as to avoid missed diagnoses and delayed treatment.