Insular carcinoma of the thyroid. A report of 8 cases.

Insular carcinoma of the thyroid (ICT) is an uncommon malignancy with intermediate morphology and behaviour between well-differentiated and anaplastic thyroid carcinoma. Eight patients with ICT underwent total thyroidectomy. A modified neck dissection was carried out in six of them. Cervical lymph nodes metastases were detected during surgery in six patients or at scintigraphy in two patients who did not undergo neck dissection. Postoperatively, a patient developed diffuse metastases not detected by 131I whole-body scintigraphy and she died of disease 6 months later despite radio- and chemotherapy. Another patient had distant metastases detected by 131I whole-body scintigraphy and successfully treated by radioiodine ablative therapy. Unfortunately, she developed other distant metastases with no 131I uptake and died of disease 23 months later despite chemotherapy. After a mean follow-up of 5.5 years, 6 patients (75%) were alive without evidence of disease. These observations confirmed the aggressiveness of ICTs that sometimes are not responsive to current available therapies. The frequent occurrence of metastases to the regional lymph node calls on for a modified neck dissection in all patients with ICT.