Histopathological features of atrophic thyroiditis with blocking type-TSH binding inhibitor immunoglobulins

To investigate the histopathological features of atrophic thyroiditis (AT) with blocking type-TSH binding inhibitor immunoglobulins (TBII), the present morphological observations were carried out employing additional immunohistochemical procedures. Moreover, these were compared with examples of goitrous Hashimoto's thyroiditis showing negative TBII (HT). There exist apparent differences between AT and HT. In particular, significant follicular atrophy with epithelial flattening including decreased positive staining of the follicular epithelial cells for thyroglobulin in AT was characteristically observed. These results suggest that the mechanism for the development of hypothyroidism in AT with blocking type-TBII might be due to suppression of thyroid cell function through the inhibition of endogenous TSH stimulation by the blocking antibody with subsequent epithelial degenerative destruction.