Adrenal tumor. The adrenal gland is above each kidney that helps regulate hormones for energy and metabolism. Tumors of the adrenal gland are commonly benign (non cancerous). These tumors can also rarely be metastatic tumors from lung cancer or rarely primary adrenal cancers. You should see your doctor for further evaluation.
Depends. A few percent of healthy folks have little round tumors in the adrenals found incidentally on scans. Radiologists can tell the ones that might be dangerous. Neuroblastoma (a young person's tumor), pheochromocytoma, or a cortisol- or aldosterone-producing tumor can all produce months / years of vague symptoms before they are detected & treated, and missed tumors can be lethal. Good luck.