Invasive micropapillary carcinoma of the breast: imaging features with clinical and pathologic correlation

The purpose of this article is to present imaging findings of invasive ductal carcinoma with micropapillary features with clinical and pathologic correlation.

We retrospectively searched our institution's surgical pathology database for patients with pathologically proven invasive ductal carcinoma with micropapillary features. Forty-one patients with images available for review were included in the study. Mammographic, sonographic, and MRI findings were assessed using the American College of Radiology's BI-RADS lexicon. Molecular breast imaging findings were reviewed using a molecular breast imaging lexicon. Imaging findings were correlated with clinical presentation and pathologic findings.

Mammographically, the most common finding was an irregular spiculated mass. Sonographically, the most common finding was an irregular hypoechoic mass with spiculated margins and posterior acoustic shadowing. With MRI, the most common finding was an irregular mass with washout kinetics, but we also observed diffuse heterogeneous nonmasslike enhancement throughout the breast. Molecular breast imaging was available for one patient and showed multicentric radiotracer uptake. Analysis of 39 pathologic specimens showed 27 (69%) with angiolymphatic invasion. Axillary nodal metastases were present in 23 patients (59%), nine (23%) with extranodal extension.

The imaging features of invasive ductal carcinoma of the breast with micropapillary features typically were highly suggestive of malignancy. The malignancies were strongly associated with lymphovascular invasion and lymph node metastases. Radiologists should be aware of the imaging features of this unusual variant and should consider axillary sonography if this entity is found in a core needle biopsy specimen.