Clinicopathologic Features of Poorly Differentiated (Insular) Carcinoma of Thyroid

ABSTRACT

PURPOSE: Well-differentiated carcinomas of the thyroid run an excellent clinical course. However 10~20% of thyroid carcinomas showed poor clinical outcomes. Insular carcinomas are an uncommon thyroglobulin-producing neoplasm, which show intermediate prognosis between well-differentiated carcinomas and undifferentiated anaplastic carcinomas, and their clinicopathologic features are poorly understood. Therefore, we aimed to investigate the clinicopathologic features and the prognosis of insular thyroid carcinomas. METHODS: We reviewed 10 patients who underwent an operation due to an insular thyroid carcinoma at Seoul National University Hospital between January 1990 and December 2001. Their clinicopathologic features and follow-up findings were retrospectively reviewed and compared. RESULTS: Four male and six female patients are reviewed, with a mean age of 54.8+/-6.4187, ranging from 37 to 69 years. Pathologically, eight of the tumors consisted of pure insular carcinoma and the others showed a papillary carcinoma as the major component and a minor insular component. The mean tumor size was 4.53 cm (4.53+/-1.4288 cm). An extrathyroidal extension was present in 7 cases and a vascular invasion in 6. Distant metastasis and local relapse of the regional lymph node were seen in 9 patients. Comparing the survivor and expired groups, all the male patients were in the expired group, and the mean tumor size was larger in the expired group (5.46 cm vs. 3.6 cm). But these differences were not statistically significant. CONCLUSION: Our study revealed that insular carcinomas have distinctive clinicopathologic features, and recognition of this histologic variant is important and significant for management of these unique tumors.