Högskolan i Skövde

Introduction: Malignancy of thyroglossal duct cyst (TGDC) is rare, usually as papillary carcinoma, and less frequently as squamous cell or follicular carcinoma. TGDC carcinoma can present as a mass arising from the neck, with or without compression symptoms. Papillary carcinoma in TGDC concomitant with another papillary carcinoma in the thyroid gland is extremely rare. Presentation of case: : 31 years old female with a neck lump since 2 years, slowly increasing in size, with mild pain while drinking fluids, and no change of voice. No past history of neck irradiation or family history of thyroid cancers. Ultrasonography of the neck showed TGDC and right thyroid nodule. Ultrasound guided fine needle aspiration and cytology of the TGDC showed TGDC papillary carcinoma. The patient underwent Sistrunk's procedure and total thyroidectomy. Discussion: Rare case of classic papillary carcinoma arising in TGDC, concomitant with another papillary carcinoma in the right thyroid nodule. Preoperative work up included US and fine needle aspiration and cytology (FNAC). Post-operative histopathology showed papillary carcinoma in the TGDC; and another in the right thyroid lobe that was a papillary carcinoma with follicular patterns. Conclusions: TGDC carcinoma concurrent with another carcinoma in the right thyroid lobe as two separate tumours are extremely rare. All patients should undergo Sistrunk's procedure, and total thyroidectomy for the thyroid tumour. Follow-up requires thyroxine replacement therapy to treat hypothyroidism and to suppress TSH in order to prevent recurrence; and neck ultrasound and thyroglobulin tumour marker to detect recurrence if present. © 2020 The Authors