Circumscribed Masses: Fat-Containing Masses

5 Circumscribed Masses: Fat-Containing Masses

Case 5.1 Galactocele

Case History

A 39-year-old woman has just stopped breast-feeding her 10-month-old infant and now finds a new breast lump.

Physical Examination

• Left breast: 3 cm lump in the upper outer quadrant

• Right breast: normal exam

Mammogram

Mass (Fig. 5.1)

• Margin: circumscribed

• Shape: oval

• Density: fat-containing

Fig. 5.1 In the upper outer quadrant of the left breast, there is a well-defined oval mass. (A) Left mediolateral oblique (MLO) mammogram. (B) Left craniocaudal (CC) mammogram.

Ultrasound

Frequency

• 10 MHz

Mass

• Margin: well defined

• Echogenicity: isoechoic

• Retrotumoral acoustic appearance: single edge shadowing

• Shape: ellipsoid (Fig. 5.2)

Fig. 5.2 Left radial breast sonogram. The mammographic mass identified in Fig. 5.1 corresponds to a well-defined mass with heterogeneous echogenicity. Milky fluid was aspirated from this mass.

Pathology

• Galactocele

Management

• Breast Imaging Reporting and Data System (BI-RADS) assessment category 2, benign finding

Pearls and Pitfalls

• Galactoceles are benign milk-filled cysts. This lesion is generally discovered either during or shortly after lactation. Mammographically, galactoceles are well-defined and oval and may appear to be completely fat density, heterogeneous density, or equal density to glandular parenchyma.

• Sonographically, galactoceles are hypoechoic, isoechoic, or heterogeneous in echogenicity. Fluid debris levels may be present.

Case 5.2 Hamartoma

Case History

A 39-year-old woman presents with a new left breast lump. Left breast sonography is initially performed. As a result of the sonogram, a mammogram has been done.

Physical Examination

• Left breast: 5 cm palpable lump in the upper inner quadrant

• Right breast: normal exam

Mammogram

Mass (Fig. 5.3)

• Margin: circumscribed

• Shape: oval

• Density: fat-containing

Fig. 5.3 At the 9 o’clock position of the left breast, there is a well-defined, oval, fat-containing mass with heterogeneous density (arrows). (A) Left MLO mammogram. (B) Left CC mammogram.

Ultrasound

Frequency

• 10 MHz

Mass (Fig. 5.4)

• Margin: well defined

• Echogenicity: heterogeneous

• Retrotumoral acoustic appearance: no shadowing

• Shape: ellipsoid

Fig. 5.4 Left radial breast sonogram. The palpable lump corresponds to a well-defined, oval, solid mass of heterogeneous echogenicity. The peripheral portion of this mass is isoechoic to fat (arrows), and the central portion is hyperechoic (arrowheads). This mass corresponds to the lesion identified in Fig. 5.3.

Pathology

• Hamartoma

Management

• BI-RADS assessment category 2, benign finding

Pearls and Pitfalls

• Hamartoma is a benign tumor that consists of mature tissues normally present in the breast. However, usually one element dominates the mass. Mammographically, the mass is well defined, but the density of the mass varies with its composition. If the mass does not have much fat, then it may be completely radiopaque. However, if the mass is a mixture of fat and other soft tissues, then it will be mixed density, as in this case. If the mass is completely radiopaque, then the differential diagnosis is fibroadenoma, cyst, or carcinoma. If the mass has mixed density, then the mammogram is diagnostic of hamartoma.

• Sonographically, hamartoma has a variety of appearances. The individual components of the tumor should sono-graphically match their corresponding normal elements within the breast. The fatty component is isoechoic to fat, and the fibroglandular elements are hyperechoic to fat.