"On ultrasound, most oil cysts are hypo-echoic with smooth walls and show neither posterior acoustic enhancement or shadowing. Echogenicity varies. Fat-fluid levels are better characterised sonographically. When present, rim calcifications will demonstrate posterior acoustic shadowing. Complex features include thick walls, mural nodularity, and internal echoic bands. A very small proportion can represent an intracystic mass."
"T1WI: circumscribed, hyperintense lesion (isointense to fat)"
Expected headings
"Associations"
"Fat debris from ruptured lipocytes tends to conglomerate to form a macroscopic pool of oil surrounded by lipid-laden macrophages or foam cells - known as an oil cyst. The wall can then calcify. Most often this occurs secondary to trauma or surgery; however, this is not always necessary."