Insular thyroid carcinoma in adolescents: a potentially lethal endocrine malignancy.

BACKGROUND: Insular thyroid carcinoma is intermediate in aggressiveness between well differentiated and anaplastic thyroid carcinomas.
METHODS: The authors describe two children with insular thyroid carcinoma who had markedly different outcomes. In the first case, a girl age 15 years, 2 months presented with a large pulsatile mass in the right thyroid lobe. In the second case, a girl age 16 years, 3 months presented after total thyroidectomy was performed elsewhere for confirmed pTNM Stage I insular thyroid carcinoma.
RESULTS: In Case 1, total thyroidectomy was performed, and histologic examination revealed insular thyroid carcinoma with lymph node involvement. Six weeks postoperatively, neck masses reappeared. There was significant radioactive iodine uptake in the thyroid bed and in a palpable right supraclavicular lymph node; this was associated with an increased serum thyroglobulin level. Ultrasound-guided biopsy of the lymph node confirmed recurrent insular carcinoma, and neck dissection was performed. Six weeks later, there was 0.35% iodine uptake in the neck, and the patient was treated with 300 mCi of (131)I. She had no signs of recurrence when last seen 22 months postoperatively. In Case 2, the patient was given 29.9 mCi of (131)I for remnant ablation. Four months postoperatively, fine-needle aspiration biopsy of a high jugular lymph node demonstrated recurrence. The patient was given 200 mCi of (131)I but had no significant response. Right modified neck dissection was performed, followed by external beam radiation. Despite aggressive treatment with a further 500 mCi of (131)I, progressive lung and mediastinal metastases developed, followed by brain metastasis. The patient died 31 months after the initial diagnosis.
CONCLUSIONS: Insular thyroid carcinoma may occur and behave aggressively in children. Vigorous initial surgical and radioactive iodine treatments are warranted.