PRIMARY PAPILLARY CARCINOMA OF THYROID IN PERSISTENT THYROGLOSSAL DUCT CYST IN ADULT

Thyroglossal duct cyst is the most common congenital anomaly of the neck. Occurrence of papillary carcinoma in the thyroglossal duct cyst in the presence of normal thyroid gland is rare. A 50 year old female presented with an anterior midline neck swelling since childhood. CT scan neck showed a multiloculated cystic mass extending from isthmus region of thyroid to hyoid bone with a centrally placed soft tissue lesion with scattered calcification. Thyroid gland appeared normal in size and parenchymal attenuation in its usual location. The mass was excised. Cut section showed a multiloculated cystic lesion having a small solid nodule with papillary excrescence. Microscopic examination showed features of papillary carcinoma of thyroid. Patient underwent total thyroidectomy with post operative radioactive iodine treatment. Histopathological examination of the thyroidectomy specimen revealed no evidence of malignancy. No evidence of recurrence during 18 months follow up.