Breast lipoma

Breast lipomas are a benign breast lesion and is classified as a BIRADS II lesion.

Clinical presentation

Lipomas are mostly asymptomatic and coincidentally discovered on routine mammography. Patients may present with a painless palpable breast lump which is soft and mobile. In these cases the diagnosis is clinically obvious.

Skin tethering or fixation are not features of lipomas.

Pathology

Lipomas are benign mesenchymal tumors that are composed of mature adipose tissue

Radiographic features

Classically it appears as a fat composed lesion seen predominantly in the subcutaneous plane; however can be seen anywhere in the breast. Ideally lipomas measure anywhere up to 2 cm in size.

Mammography

Typically seen as a radiolucent mass with no calcification (in rare situation there may be areas of fat necrosis presenting as calcification). They may have a thin, peripheral, fluid density capsule. Mammographic detection may be easier in a dense breast. In the vast majority of cases lipoma is incidentally seen on routine screening.

Ultrasound

May be seen as a rounded lesion that is iso-echoic or at times slightly hyperechoic to surrounding fat. Occasionally a lipoma can be hypoechoic ⁴. Multiple thin echogenic septations may be seen running parallel to the skin surface. The lipoma can be readily distinguished from a hamartoma by the ultrasound and mammogram appearances. Compressibility of the lesion can also be demonstrated on ultrasonography.

These lesions are also found in males.

Treatment and prognosis

These lesions are rarely a diagnostic or imaging dilemma. Enlargement of a lipoma is an indication for biopsy. They rarely undergo malignant transformation and are not associated with an increased risk of developing breast cancer.