Adrenal gland tumour. Light micrograph of a section through a human adrenal (suprarenal) gland tumour. The tumour (neoplasm) is a benign (non- cancerous) phaeochromocytoma, which affects the inner region (medulla) of the adrenal gland. The adrenal glands are situated on the surface of the kidneys, they release various hormones including adrenaline. Phaeochromocytoma causes uncontrolled secretion of the hormones adrenaline and noradrenaline, which results in raised blood pressure, palpitations and increased heart rate. Removal of the tumour or even the whole gland (adrenalectomy) often cures the condition. Magnification unknown.