Since the original description of poorly differentiated or insular thyroid cancer in 1984, case reports and small series have confirmed the position of this histologic variant as intermediate in prognosis between well-differentiated thyroid cancer and anaplastic thyroid cancer. This retrospective analysis of 127 patients with FVPTC or FTC identified 14 patients who met the criteria for an insular lesion. There was a significant difference in survival between these 14 patients with poorly differentiated lesions and the remainder, as well as differences in size and metastasis at time of diagnosis determined by univariate and logistic regression analysis. Unfortunately, as is the case with other published reports, the number of patients in the insular category was small—too small, probably, from which to draw meaningful conclusions. The age of the patient, size of the tumor, and presence of metastases, however, are still important predictive variables. Do these findings indicate altering treatment of patients with thyroid cancer, as the term poorly differentiated would suggest? Probably not, since the important information would seem to be contained in the traditional TNM, AMES, AGES, and MACIS staging systems. Still, I suspect that we all will be a little more cautious in our treatment of and follow-up with patients when our pathologist calls 2 days postoperatively to advise us that the lesion was an "insular thyroid tumor."
Fabri PJ. Multivariate Analysis of Clinicopathologic Parameters for the Insular Subtype of Differentiated Thyroid Carcinoma—Invited Critique. Arch Surg. 2001;136(8):944. doi:10.1001/archsurg.136.8.944