The Clinical Management of a Patient with Insular Thyroid Carcinoma

Abstract

Insular carcinoma is a rare tumor that was first described as a unique histological subtype of thyroid cancer, in 1984. The World Health Organization (WHO) classified insular carcinoma as a separate existence and as a larger group of poorly differentiated thyroid carcinomas, in 2004. It was described as a thyroglobulin producing non-papillary non-follicular thyroid carcinoma, and it possesses an intermediate behavior between well-differentiated (papillary and follicular carcinoma) and anaplastic thyroid carcinomas with regard to both histological features and biologic aggressiveness. Insular carcinomas represent 0.4–6.2% of all thyroid carcinomas. Despite its rarity, it represents the main cause of death from non-anaplastic follicular cell-derived thyroid cancers. Distant metastasis and lymph node metastasis are most frequent, and moreover, 20% of patients with insular carcinoma have distant metastasis at the time of diagnosis. In patients with insular carcinoma, radioiodine uptake ability of primary tumor and distant metastasis is more than 80%. The current approach of management is total thyroidectomy followed by radioiodine therapy and close follow-up. In the view of the fact that worse prognosis, multidisciplinary approach combining surgery, bone-directed agents, and external radiation therapy concomitant with radioiodine therapy may provide treatment success and significant improvement in progression-free survival.