Pindborg Tumor : Microscopic
Calcifying epithelial odontogenic tumor (CEOT) is composed of sheets, nests, or strands of polygonal epithelial cells in a background with variable amounts of fibrous stroma. The tumor cells have abundant eosinophilic cytoplasm, distinct cytoplasmic borders, and prominent intercellular bridges. Some cases show considerable nuclear pleomorphism with giant nuclei - a feature not indicative of malignancy. Mitotic activity is not increased. Large areas of amyloid or amyloid-like amorphous, eosinophilic, hyalinized extracellular material are present. Calcifications develop within these amyloid-like areas and can form concentric rings known as Liesegang rings. Some cases are composed almost entirely of epithelial cells with minimal amyloid-like deposits and may even lack calcifications altogether. Others show only small nests and strands of epithelial cells engulfed by large diffuse areas of amyloid. A clear cell variant with cystic growth pattern has also been described.