The most common causes of strong echogenicity in the adrenal glands include adrenal hemorrhage, neuroblastoma, extralobular lung isolation and exophytic renal tumors, but also adrenal adenoma, adrenal carcinoma, adrenal hyperplasia, duplicated renal system, nephroblastoma, congenital mesangial nephroma (CMN), lymphatic duct malformation, and mesenteric and intestinal duplication cysts. I. Adrenal hemorrhage 1. Ultrasound manifestation: strong echogenic light masses are seen in the adrenal region, with usually homogeneous echogenicity and central cysticity, located on the right side or bilaterally. 2. Significance: A solid strong echogenic mass in the adrenal gland may represent recent adrenal hemorrhage. The diagnostic point is the absence of internal blood flow and the change in appearance of the lesion on serial ultrasound examinations, followed by a central hypoechoic area, after which the appearance tends to be cystic and the lesion shrinks. In case of degeneration or necrosis, calcifications may be present in the tissue. 3. 75% of hemorrhages occur in the right adrenal gland and may be associated with a shorter right adrenal vein. Hypoxia and increased intravascular pressure have also been proposed as possible causes of intrauterine adrenal hemorrhage, but the exact etiology is not fully understood. 4. Since it is difficult to differentiate adrenal hemorrhage from neuroblastoma in late pregnancy, postnatal follow-up is recommended even if the diagnosis of adrenal hemorrhage is presumed. Neuroblastoma 1. Ultrasound presentation: Neuroblastoma is usually detected in late pregnancy. The mass may be cystic, solid or mixed echogenic and may have calcified margins, usually located on the right side, displacing the adjacent kidney downward and laterally. Fetal edema and liver and placental metastases have also been reported. The presence of liver metastases supports the diagnosis of neuroblastoma. 2. Significance: Neuroblastoma is the most common adrenal tumor in fetuses. It resolves spontaneously in up to 40% of cases, but surrounding foci of calcification may persist. Fetal magnetic resonance imaging helps to understand in detail the anatomy of the tumor and the extent of the lesion. 3. Prenatal findings of adrenal masses are usually detected during ultrasound examinations performed after 32 weeks of gestation and are first observed at 18 weeks of gestation. Since the first case report in 1983, more than 55 cases of prenatal neuroblastoma have been reported in the literature. In North America, 100 children per year are diagnosed with neuroblastoma prenatally or before 3 months of age. Because most of these tumors are present before birth, the rate of prenatal diagnosis is likely to continue to rise. 4. If an adrenal tumor is detected during prenatal ultrasound for unrelated reasons, and the fetus is otherwise developing normally, the infant should be re-examined with ultrasound after delivery. Urine catecholamine measurements may also be helpful in differentiating neuroblastoma from other possible masses, including adrenal hemorrhage and vascular malformations, but a negative test result does not rule out this diagnosis. Also, maternal hypertension and tachycardia may be present due to increased catecholamines.