CONICET | Buscador de Institutos y Recursos Humanos

Thyroglossal duct cysts (TGDC) are the most common thyroid developmental anomalies accounting for 75% of midline neck tumors in children and 7% in adults. Carcinoma of the TGDC has been reported in less than 1% in adults. Objective: Describe the case of a pediatric papillary carcinoma of the TGDC. Case report: A 12 year old girl presented with an asymptomatic fast growing neck mass noticed 7 months previous to consultation. Her past medical history was unremarkable. US revealed a cystic-solid mass of 21 x13 mm with microcalcifications with a normal thyroid gland. With a presumptive diagnosis of TGDC a Sistrunk procedure was performed. Histological evaluation revealed a papillary carcinoma of 12x6mm in the wall of a 35x25x25mm TGDC. The patient was referred to our Unit for follow up. Physical examination revealed an euthyroid pubertal girl with a non palpable thyroid gland without palpable cervical nodes. Neck US showed a normal eutopic thyroid gland without suspicious adenopathies. Neck and chest CT scan were normal. Histologic examination after total thyroidectomy revealed no tumor. Postoperatively, an ablative 131 I dosis of 50 mCi was administered, WBS performed on day 5 revealed focal radioiodine uptake confined to the inferior cervical region. Cervical US showed a right yugular adenopathy of 15x7mm with an heterogeneous vascularized rounded area. FNAB cytology was positive for papillary carcinoma with positive thyroglobulin in the needle wash-out. Surgical excision was performed with histologic diagnosis of papillary metastatic infiltration. Conclusions: Although exceptional in pediatrics rapid growth of a thyroglosal duct cyst excluding infection and/or US signs suggestive of malignancy should alert of the possibility of TGDC carcinoma. The lack of thyroid involvement does not rule out the presence of metastasis and follow up should be the same as for differentiated thyroid cancer.