An autoimmune disease. MC cause of Hypothyroidism
Gross: The gland is diffuse symmetrically enlarged, sometimes nodular. Cut surface is fleshy and resembles lymphnode
Microscopy: The most prominent feature is extensive lymphocytic infiltrate with formation of germinal centers. As a consequence of destruction, the follicles show varying degree of atrophy. Many of the follicular epithelial cells show evidence of degeneration in the form of a “swollen cell” . This cell is called as Hurthle cell. Sometimes referred to as oncocytes/oxyphilic cells.
Hurthle cell is a follicular epithelial derived cell, large, polygonal and has abundant eosinophilic granular cytoplasm ( because of loads of mitochondria within them). The nucleus is hyperchromatic and has a prominent nucleoli.
The colloid within the follicle is scanty or absent.