Fig. 2
From: Ectopic intrathyroidal thymic tissue in an adult patient: a case report and review of the literature
Microscopy: H&E sections (E–H) show an encapsulated mass with a thick fibrous capsule and intersecting fibrous bands separating it into lobulated architecture with cellular lobules resembling the normal thymic cortex composed of scattered bland thymic epithelial cells in a dense background of small lymphocytes (Immature T cells). Immunohistochemistry: The scattered epithelial tumoral cells show immunoreactivity for CKAE1/AE3 (D) and P63 (J). Background lymphoid cells show diffuse immunoreactivity for LCA (Leukocyte common antigen), CD3 (K), CD43 (B), and CD99 (C) but are negative for CD20 (A). The proliferation index (KI67) (I) is very high in lymphoid cells