Unknown Case: 74-year-old Woman With a Developing Asymmetry Within a Breast Hamartoma.

Abstract

A 74-year-old female with a known mammary hamartoma in the inner right breast presented with a palpable lump in the left breast. Bilateral diagnostic mammogram (Figure 1) and targeted US (Figure 2) were performed. On diagnostic imaging, the left breast workup was negative. Incidentally noted was a developing asymmetry within the known right breast hamartoma in the lower inner right breast (Figure 1). Targeted diagnostic US showed a circumscribed solid lesion with mixed hyperechoic and hypoechoic components, consistent with the known hamartoma at 4 o’clock in the right breast. Within this hamartoma, there was a distinct 5-mm hypoechoic mass (Figure 2). Since breast hamartomas are a subtype of fibroepithelial lesion, they contain breast epithelium, collagenous stroma, and adipose tissue. The differential diagnosis for a breast mass within a hamartoma therefore includes lesions of epithelial origin, such as invasive ductal or lobular carcinoma, high-risk lesions, cysts, or lesions of stromal origin, such as pseudoangiomatous stromal hyperplasia. Lipid-rich carcinoma could be considered, although the long history of a stable fat-containing circumcised mass (presumed hamartoma) makes this rare entity less likely.