What is a defining characteristic of invasive lobular carcinoma?

Invasive lobular carcinoma is characterized by the tendency to present as multiple lesions rather than as a single lump. This is particularly notable because lobular carcinoma often manifests as small, non-palpable tumors that can be dispersed throughout the breast tissue. This multifocal nature is a hallmark of the disease, which can complicate diagnosis and treatment planning.

While other characteristics such as firmness or growth patterns of tumors may apply to various breast cancers, they are not specific enough to define invasive lobular carcinoma. For instance, lumps being firm and round typically describe other breast lesions, whereas rapidly growing solid masses are more characteristic of certain types of invasive ductal carcinoma. Similarly, lobular carcinoma does not conform to being localized to a single quadrant; rather, its multifocality challenge is one of the reasons for increased surveillance in patients with a history of breast cancer. Understanding this defining characteristic helps clinicians recognize and manage the nuances of this type of breast cancer effectively.