The purpose of this study was to determine whether lymphocytic infiltration surrounding and/or inside the tumor would predict a favorable prognosis in patients with papillary thyroid carcinoma (PTC). The data obtained from twenty-five patients of PTC with both classic (n=15) and microcarcinoma (n=10) subtypes who were followed up for an average of 6.6 years (5 to 10 years) were evaluated retrospectively. The patients were subdivided according to whether or not there was lymphocytic infiltration in the thyroid gland. Group A consisted of 12 patients with lymphocytic infiltration whereas group B consisted of 13 patients with no lymphocytic infiltration.
There were no differences in age, sex, initial tumor size, type of initial treatment, or antithyroid antibody frequencies between the two groups. None of the patients in group A had recurrence of tumor, but three patients in group B had recurrence. The duration between initial treatment and recurrence in these patients was 3, 4 and 6 years, respectively. In relation to the clinical class at the time of initial treatment, recurrence was detected in one case in each of classes I, II and III. Recurrence was detected in only one patient whose tumor size was less than1cm (microcarcinoma) whereas 2 others who had primary tumor size ranging from 1 to 3 cm (classic subtype) recurred. All patients were alive and tumor free at their last visit. Our preliminary results suggest that lymphocytic infiltration of the thyroid gland in PTC seems to be a favorable prognostic marker. But , further studies of larger groups of patients are necessary to determine the role of lymphocytic infiltration in the prognosis of PTC.
Keywords: Papillary thyroid carcinoma, lymphocytic infiltration, histologic subtypes, prognosis