Pathologic features of polycystic thyroid disease: Comparison with benign nodular goiter
Polycystic thyroid disease (PCTD) is characterized by multiple thyroid cysts detected by ultrasonography, the absence of thyroid autoantibodies, and susceptibility to the development of hypothyroidism due to a high iodine intake  . We previously reported that hypothyroidism induced by PCTD accounted for about 7% of all causes of hypothyroidism in a region with a high iodine intake  . We speculated that the development of hypothyroidism was due to a decreased volume of normal thyroid
... e-producing tissue because of multiple cysts in PCTD. From the previously published images of ultrasonography, PCTD may have been classified as multinodular goiter thus far. We have to obtain histopathological information on PCTD in order to clarify whether it is different from multinodular goiter. We retrospectively identified three patients with PCTD who underwent thyroidectomy because of Abstract. Polycystic thyroid disease (PCTD) is characterized by multiple thyroid cysts detected by ultrasonography, the absence of thyroid autoantibodies, and susceptibility to the development of hypothyroidism due to a high iodine intake. It is necessary to obtain histopathological information on PCTD in order to clarify the cause of hypothyroidism. We retrospectively reviewed three patients with PCTD and small papillary thyroid cancer who underwent thyroidectomy. We observed the thyroid tissues pathologically in areas with and without multiple cysts, and compared them with those of multinodular goiter with cysts. In the patients with PCTD, there were multiple enlarged follicles that resembled enlarged normal follicles and differed from those found in multinodular goiter in terms of their shape. Huge follicles corresponded to the cysts that were detected by ultrasonography. Each follicle contained colloid. Follicular cells in enlarged follicles comprised low cuboidal epithelium that appeared normal. These findings were common in the 3 patients with PCTD. In Conclusion the PCTD patients had multiple enlarged follicles that seemed to decrease the total number of follicular cells, and may be a cause of hypothyroidism. We believe that PCTD is a new entity of thyroid disease based on the pathological findings.