Slide 1.19
This a 9.0 cm left adrenal mass in a 46 year old man with difficult to control hypertension. He was found to have high levels of catecholamines and metanephrines in urine. The mass is dark brown and hemorrhagic. Note the residual normal adrenal gland with distinct thin rim of bright yellow cortex and brown medulla. Pheochromocytoma can be sporadic or can be part of MEN type II A and II B syndromes.

Slide 1.20
At low power a pheochromocytoma has a nested appearance, with tumor cells clustered in small alveoli separated by a rich capillary network. This nested arrangement (called “zellballen”) is characteristic for neuroendocrine tumors.