| - Follicles are small to medium sized and irregularly formed. Colloid within the follicular lumen is scant with scalloped margins.
- The epithelium is tall and columnar. Crowding of cells leads to formation of papillae, which in contrast to papillary carcinoma lack a fibrovascular core.
- The inflammatory infiltrate consists of small lymphocytes, not staining for intracytoplasmic immunoglobulin. In addition, positively staining plasma cells infiltrate the septae, some aligned in chains in between follicles. |
