A case of papillary carcinoma arising from a thyroglossal duct cyst is reported. A 26-year-old woman with IgA nephropathy was referred to our clinic for tonsillectomy. Although she did not have any symptoms, we felt a mass in her anterior neck. MRI showed a cystic tumor with a solid lesion. Fine-needle aspiration biopsy of the mass did not reveal any malignant cells. We resected the mass and performed tonsillectomy at the same time. Histopathological examination of the surgical specimen showed that the solid lesion contained a papillary carcinoma arising from a thyroglossal duct cyst. The postoperative examinations (CT scan, neck ultrasonography and PET-CT) revealed no thyroid cancer or metastatic lymph nodes. As the malignant lesion was limited to the cystic tumor, we followed the patient up without any additional treatment. Until now, one year since the surgery, she has shown no sign of recurrence.
Thyroglossal duct cyst has been reported to be infrequently (with a probability of 1-2%) associated with malignancy. We suggest that it is important to consider malignancy, especially when the cyst contains a solid component, and to take a careful aim at the lesion during fine-needle aspiration biopsy. Measurement of the serum thyroglobulin may also contribute to an accurate diagnosis.
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