What is an adrenal myelolipoma, and what are its CT and MRI features?
Adrenal myelolipoma is the second most common benign neoplasm of the adrenal gland and is composed of variable amounts of fat and hematopoietic tissue. It occurs with equal frequency in men and women, most often in the fifth through sixth decades of life, and is usually asymptomatic.
On CT and MRI, a well-circumscribed adrenal gland nodule or mass is visualized that contains macroscopic fat, which is the key diagnostic feature. Macroscopic fat has similar attenuation and signal intensity properties as subcutaneous and visceral fat within the torso. Non-fatty enhancing soft tissue components are also often present. Calcification may be seen in up to 20% of cases, and hemorrhagic components may be seen in up to 10% of cases.