- A 45 years old lady
- Came for screening mammogram
- No family history of breast cancer
- Moderately dense breasts with symmetrical parenchymal pattern
- A well-defined, low-density oval-shaped lesion in the right breast
- The lesion shows thin rim/wall calcification
- No stromal distortion
- A few scattered benign calcifications in both breasts
- No suspicious clustered microcalcification
- No nipple retraction or skin thickening
- No abnormal enlarged axillary node
Diagnosis: Mammary oil cyst (BIRADS 2: Benign)
- Oil cyst refers to benign breast lesion where an area of focal fat necrosis becomes walled off by fibrous tissue
- Occurs across all age and ethnic groups
- Usually asymptomatic, can be tender or non-tender palpable lump, bruising if recent trauma
- On mammogram it is seen as radiolucent mass of fat density, with or without wall calcification. Lesion is well circumscribed with a thin capsule. Rarely fat fluid level may be present
- 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.
- Treatment is usually not required.
- Biopsy or aspiration is not recommended.