Granular Cell Tumor
Granular cell tumors are composed of round, polygonal, or spindle-shaped cells with nuclei ranging from small, hyperchromatic, pyknotic to large vesicular nuclei with punctate nucleoli. Occasional nuclei may show intranuclear pseudoinclusions (seen here in the center of the image) or degenerative-type atypia. The cytoplasm is eosinophilic with fine to coarse granules as well as large round droplets that are PAS-positive, diastase-resistant. These granules represent phagolysosomes accumulated in the cytoplasm. Ultrastructurally, they appear as membrane-bound vacuoles containing myelin figures, fragmented rough endoplasmic reticulum, and mitochondria. In addition, there is a second population of cells with angulated bodies. There is replicated basal lamina material around the granular cells.