Malignant tumours of the adrenal gland are cancerous growths that have the potential to spread (metastasize) to other parts of the body. Malignant adrenal gland tumours are rare.
Adrenocortical (or adrenal cortical) carcinoma is the most common malignant tumour of the adrenal gland. It develops in the cortex (outer layer) of the adrenal gland.
Pheochromocytomas start in chromaffin cells of the medulla (inner layer) of the adrenal gland.
Most pheochromocytomas start in the adrenal gland, but they can also start in other parts of the body. These are called extra-adrenal pheochromocytomas or paragangliomas.
Other tumours can occur in the adrenal glands and are extremely rare.