Abnormal density shadow in the left adrenal region, usually found after CT or enhanced CT examination, refers to the presence of abnormal hyperplasia or cyst in the adrenal region, which may be adrenocortical hyperplasia, adrenocortical adenoma, pheochromocytoma, adrenocortical carcinoma and so on. 1. Adrenocortical hyperplasia: nodular hyperplasia of the adrenal gland is common, and its CT manifestation is that the gland has limited nodular bumps with irregular edges, which may be slightly hypodense on CT. Plasma adrenocorticotropic hormone level may be elevated. 2. Adrenocortical adenoma: its CT may manifest as round or oval soft tissue mass, and the enhanced scan shows homogeneous or heterogeneous transient enhancement of the mass. 3. Pheochromocytoma: CT may show a round or oval adrenal mass with uneven density and occasional calcification. The tumor is obviously strengthened on enhanced scan. 4. Adrenocortical carcinoma: CT may show a large lobulated mass with uneven density, sometimes with calcification. After enhancement, there is an irregular strengthening ring around the periphery of the mass, and the low density area in the necrotic part of the center is not strengthened. If abnormal density shadow in adrenal region appears, it is recommended to consult the doctor in time, improve relevant examination, and take corresponding treatment after clear diagnosis.