Amyloid goiter: Microscopic section with Congo red stain

Microscopic section (Congo red and hematoxylin and eosin stains, magnification x 100) of the thyroid from a patient with an amyloid goiter stained with Congo red shows green birefringence under polarized light microscopy. Note deposition of amyloid material surrounding a thyroid follicule (F) and in the perivascular (V) space.