“Metastatic Invasive Breast Carcinoma”

Although much less common than invasive ductal carcinoma, it is vitally important for radiologists to understand the common imaging presentation and metastatic patterns of invasive lobular carcinoma. The most common mammographic findings include regions of architectural distortion or focal asymmetry; occasionally, the “shrinking” breast sign may be seen. Compared to IDC, ILC is more likely to be multicentric or bilateral and has a similar propensity for region lymph node spread. The metastatic pattern is a distinguishing feature with ILC more likely to metastasize to the gastrointestinal system, gynecologic organs, and peritoneum-retroperitoneum. A basic understanding of these differences will help suggest the appropriate diagnosis and guide management decisions.