Breast Lipoma

History: 50 year old woman presenting for screening mammogram.

Breast Lipoma: mediolateral oblique (MLO) image of the right breast demonstrates a fat containing circumscribed oval mass in the posterior breast compatible with a breast lipoma, BIRADS category 2, benign.

This is a case of a breast lipoma. This is a benign tumor of the breast composed of mature adipose (fat) cells. They can be present in the breast, axilla, chest wall, or subcutaneous tissues, and typically appear circumscribed, oval or round. If they necrose, they can show dystrophic calcification. On ultrasound they appear hyperechoic or isoechoic to subcutaneous fat. The classic differential diagnosis of fat containing breast masses includes:

1. Hamartoma (fibroadenolipoma, or breast within breast)

2. Oil cyst (fat necrosis)

3. Galactocele in lactating or post-lactation patients

4. Lymph node

5. Steatocystoma multiplex

6. Liposarcoma – very rare, large fatty mass with thick septations and soft tissue nodules