Fig. 4

The hematoxylin and eosin (H&E) stained tissue sections revealed the typical pathological characteristics of parathyroid adenoma under the Olympus CX31 biological microscope. The capsule can be seen in the tumor tissue. There was a small amount of compressed residual parathyroid tissue outside the capsule. The tumor parenchyma was mainly composed of chief cells. Tumor cells were arranged in clumps, cords, or acinar-like structures. Large and scattered eosinophils can be seen in the tumor tissue. The cytoplasm of these eosinophils was stained red. a H&E stain, magnification 100×; b H&E stain, magnification 200×