Ectopic Thyroid Tissue in the Mediastinum Characterized by Histology and Functional Imaging with I-123 SPECT/CT

Figure 2

Histological image of ectopic thyroid tissue in mediastinum. Fragments of benign thyroid tissue identified in the cell block prepared from the transbronchial needle aspiration. Bland, uniform thyroid epithelial cells are disposed in the follicular units characteristic of benign thyroid tissue (blue arrow), with focal presence of intrafollicular colloid (red arrow). There is mild perifollicular hyalinization (Hematoxylin and Eosin, 20x).