Invasive mucinous carcinoma of the breast

Abstract

Mucinous carcinoma of the breast is one of the rarer forms of intramammary cancer, often presenting as a lobulated, fairly well circumscribed mass on mammography, sonography, and gadolinium-enhanced magnetic resonance imaging. It accounts for 1% to 7% of all breast cancers and generally carries a better prognosis than other types of malignant breast cancers. Metastatic disease occurs at a lower frequency than in other types of invasive carcinoma. We present an atypical case of mucinous carcinoma in a woman who presented with a palpable intramammary lymph node metastasis from an unknown breast primary. Subsequent magnetic resonance imaging and percutaneous biopsy demonstrated histologic findings consistent with a mixed mucinous neoplasm with a micropapillary pattern.

Figure 1.

Spot mammographic view of the left breast demonstrates a 7 mm ovoid mass at the palpable area of concern as designated by a radiopaque marker.

Figure 2.

Sonographic image of the left breast demonstrates a 7 × 6 mm mixed echogenicity ovoid mass at the 2:00 position, approximately 10 cm from the nipple. Histologic sampling yielded findings consistent with a metastatic lymph node from an occult breast primary.

Figure 3.

Two gadolinium-enhanced MR images of the left breast demonstrate multiple areas of nonmasslike enhancement (yellow arrows) within the lower inner and lower outer quadrants of the left breast. An area of masslike enhancement (red circle) is also identified at the 7:00 position.