Invasive lobular carcinoma (ILC) is the second most common type of breast cancer after invasive carcinoma, no special type (NST).  However, there are several subtypes of ILC, with the pleomorphic variant getting a lot of attention because most studies suggest it behaves in a more aggressive manner than typical ILC. Pathologists also recognize other variants of ILC based upon how they look under the microscope, including signet ring type, solid type, alveolar type, among others.  This was mostly an academic issue but new research suggests there may be more to it.

The journal Cancer published an article this month from a group of researchers who looked at 530 ILCs. They found that the typical, or classic, ILC had a lower grade, a lower chance of having metastases to axillary lymph nodes, and fewer nodes involved if there was metastatic disease. Patients with the other variants had a much higher incidence of “breast-related events”, and they showed that in these patients there was a trend for a reduction in overall survival.

Currently, not all pathologists comment on these special variants, with the exception of pleomorphic invasive lobular which most pathologists recognize. This study was just released this month so we will see if it changes the way pathologists diagnose invasive lobular carcinoma.

© 2008-2010 Seattle Breast Pathology Consultants, LLC. All rights reserved.