Genome-wide studies in thyroid neoplasia

Prognostic factors and follow-up of patients with differentiated thyroid carcinoma with false negative or nondiagnostic FNAC before surgery. Comparison with a control group

Since the clinical implementation of fine needle aspiration cytology (FNAC) to diagnose thyroid carcinoma, few patients remain misdiagnosed and little is known about their clinical outcomes. An observational retrospective study was carried out to analyse prognostic factors and follow-up of patients with differentiated thyroid carcinoma (DTC) not disclosed by FNAC before surgery, compared to a control group. From October 2003 to July 2010, 308 patients underwent surgery as treatment for nodular goitre and 53 had DTC. Cases were 12 subjects with DTC and benign (n = 7) or nondiagnostic (n = 5) FNAC. Controls were 39 subjects with DTC and suspicious (n = 19) or malignant (n = 20) FNAC. Prognostic factors, recurrence and survival rates were compared. Cases had longer time from FNAC to surgery than the control group (86.8 ± 74.1 vs. 16.4 ± 23.8 weeks; P < 0.001), higher prevalence of follicular carcinoma (33.3 vs. 2.6%; P = 0.009), and of two-time total thyroidectomy (75 vs. 30.8%; P = 0.016). Average follow-up was 42.7 ± 25.3 months (2-86 months). There were no deaths. Disease-free survival for cases was 66.9 ± 5.8 months, and for controls 78.7 ± 3.9 months (P: ns). In patients with DTC, the result of the FNAC performed before surgery was not an independent predictor of recurrences or mortality in the first 7 years of follow-up. Thus, false negative or nondiagnostic FNAC in a patient with DTC does not seem to be a primary prognostic factor, but it may reveal other adverse prognostic factors such as longer time to therapy and higher prevalence of follicular carcinoma that may influence long-term outcomes.

Follicular thyroid carcinoma

Follicular thyroid carcinoma is being diagnosed less and less frequently despite the increasing incidence of well-differentiated thyroid carcinomas everywhere. This review will discuss the reasons underlying such an observation focusing on the evolution of the morphological and immunohistochemical diagnostic criteria of follicular thyroid tumors. It will address the differential diagnosis between follicular carcinoma and three tumor types--follicular adenoma, follicular variant of papillary carcinoma and poorly differentiated carcinoma--as well as the problems raised by the newly described categories of follicular tumors: follicular tumor of uncertain malignant potential, well-differentiated tumor of uncertain malignant potential and well-differentiated carcinoma, not otherwise specified. Finally, the prognostic and therapeutic significance of some promising molecular biomarkers will be discussed within the frame of the aforementioned histopathological classification.