Which statement best defines pheochromocytoma?

• A. Catecholamine-secreting adrenal tumor derived from chromaffin cells
• B. Adrenal cortical tumor secreting aldosterone
• C. Pituitary tumor secreting ACTH
• D. Neuroendocrine tumor arising from pancreatic islets

Answer: (A)

Pheochromocytoma is a catecholamine-producing tumor of the adrenal medulla arising from chromaffin cells. This explains why the condition presents with episodes of hypertension, headaches, sweating, and tachycardia—the hormones it releases (epinephrine and norepinephrine) drive these sympathetic symptoms. The other options point to different tumor sites and hormone secretions: an adrenal cortical tumor would secrete aldosterone, causing mineralocorticoid effects; a pituitary tumor secreting ACTH would lead to cortisol excess (Cushing syndrome); a pancreatic islet tumor would secrete hormones like insulin or gastrin. So the defining feature is a chromaffin-cell–derived tumor in the adrenal medulla that secretes catecholamines.