Histopathological Characterization and Whole Exome Sequencing of Ectopic Thyroid: Fetal Architecture in a Functional Ectopic Gland from Adult Patient

Figure 2

Immunohistochemistry expression of specific thyroid genes in ectopic and normal thyroid tissue. (A) Representative images of samples 2, 3, 4, and 6 showing goiter; (B) sample 5 exhibiting normal thyroid pattern; and (C) normal thyroid sample. TG: intense diffuse TG expression in the lumen of all follicles of the ectopic and normal samples; weak or negative cytoplasmic staining in cell follicles (a–c). TPO: intense immunostaining in the cytoplasm of thyrocytes and in the apical membrane of the follicles of ectopic samples examined, similar to the normal thyroid sample (d–f). TSHR: scattered staining in the cytoplasm of thyrocytes in ectopic and normal samples (g–i); magnified representative image showing basolateral membrane staining in some cells. NKX2.1: strong diffuse nuclear immunostaining was observed in most of the nuclei of the ectopic and normal thyroid tissues (j–l), except for sample 2, showing 10% positive nuclei. PAX8: moderate expression observed in around 80% of nuclei of normal and ectopic thyroid tissues (m–o) with focal areas of low nuclear expression in the ectopic samples. In sample 2, only 20% of positive nuclei were positive and scattered cytoplasmic expression was also observed. NIS: cytoplasmic staining was observed in all samples (p–r), and basolateral membrane positivity was observed in up to 10% of cells of samples 3, 4, and 5 (p, q). Normal samples had a similar pattern of 20% positivity in the basolateral membrane and cytoplasmic staining (r). Thyroxine (T4): moderate or intense diffuse expression in follicular colloid was observed, although some follicles showed low immunostaining, similar to the normal thyroid (s–u). Magnification at 40x except for the images of a, c, s, and u at 20x.