Fig. 2

External appearance and histopathology of the pheochromocytoma. a External appearance of the resected tumor, 6.5 cm in diameter and black in color, from the medial branch of right adrenal gland with enlargement of the lateral branch. b Histopathology revealed that the majority of cells were chromaffin-like cells with a very rich vascular sinus (thin blue arrow). Beneath the tumor capsule, there were multifocal oval eosinophilic cells with oval nucleus (thin black arrow). Adrenocortical hyperplasia was also revealed (bold black arrow; HE staining, 100×). Positive immunohistostaining is shown for CgA (c 200×), CD56 (d 200×), and Ki67 (e 100×) for chromaffin-like cells. No positive ACTH immunostaining was noticed (f 200×). Positive immunohistostaining is shown for CRH (g 400×) and Melan-A (h 200×) in the eosinophilic cells