Pindborg tumor: Not all Congo red-positive amyloid-like areas show apple-green birefringence under polarizing microscope

摘要

Histopathological and histochemical-stained microphotographs of the Pindborg tumor. (A) Low-power microphotograph showing that the tumor was composed of many areas or globules of amorphous, eosinophilic, and amyloid-like material (right lower part) and some foci of calcification (left half and right upper part) in a fibrous connective tissue stroma. (B) Medium-power microphotograph exhibited many areas or globules of amorphous, eosinophilic, and amyloid-like material in a fibrous connective tissue stroma. (C) Medium-power microphotograph demonstrating mainly some foci of calcification in a fibrous connective tissue stroma. (D) High-power microphotograph showing nests or islands of odontogenic epithelial cells in a background of eosinophilic and amyloid-like areas. (Hematoxylin and eosin stain; original magnification; A, 4 × ; B and C, 10 × ; D, 20 × ). (E, F, G, and H) By Congo red stain, the amyloid-like areas were brick-red and only very small focal spots of the brick-red areas exhibited apple-green birefringence under polarizing microscope (F and H). When the amyloid-like globules were surrounded by a big mass of odontogenic epithelial cells, it might mimic a cribriform appearance (G and H) (Congo red stain, original magnification; E and F, 10 × ; G and H, 20 × ). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)