Prognostic factors in follicular carcinoma of the thyroid.

Although there are numerous publications on the nomenclature, morphological diagnostic criteria, and prognostic factors of follicular carcinoma of the thyroid, these issues remain controversial. We present the findings of a retrospective and comparative study of 82 patients who underwent thyroid surgery for thyroid neoplasms. Of these patients, 58 had follicular carcinoma, 12 had atypical adenoma, and the remaining 12 patients had adenoma with partial capsular invasion in the surgical specimen. The goal of the study was to determine diagnostic criteria and prognostic factors in follicular carcinoma. Our results showed that encapsulated thyroid follicular neoplasms should be considered malignant when they demonstrate total capsular invasion and/or vascular invasion. Statistical analysis of the cases of follicular carcinoma showed that higher morbidity rates were seen in the patients with metastasis at the time of diagnosis, with extensively invasive tumors, with age older than 35 years, and with tumors with simultaneous vascular and capsular invasion. The accumulated survival rate over 5 years based on mortality was 91%, and based on morbidity it was 71% (84% for patients with encapsulated tumors and 56% for patients with extensively invasive tumors). In the univariate survival study based on morbidity, we found a relationship with the following parameters: metastasis at the time of diagnosis, grade of local invasion, presence of capsular and vascular invasion, cellular atypia, histologic pattern (insular vs others), presence of thyroid nodule, and age of the patient at the time of diagnosis. In the multivariate survival study based on morbidity, the factors that showed prognostic value were metastasis at the time of diagnosis, grade of local invasion, and age of the patient at the time of diagnosis.