Sphenoid Brown Tumor Associated with a Parathyroid Carcinoma
(a) Sheets of polygonal cells with clear cytoplasm and monotonous nuclei without atypia, H&E stain, ×400. (b) Thick fibrous bands, H&E stain, ×50. (c) Focal capsular invasion without perforation, H&E stain, ×50. (d) Vascular invasion, H&E stain, ×100.