A challenging characteristic of inflammatory breast cancer (IBC) to physicians is the lack of a collective tumor mass. Instead of a solid mass, the tumor appears as sheets or cords throughout the breast, thus mammography is typically not useful for diagnosis (Dawood & Valero, 2012). The best way to confirm a diagnosis of IBC is through a skin biopsy of the affected breast (Dawood et al., 2011). Another hallmark characteristic of IBC is how the tumor cells invade the dermal lymphatic tissue of the breast. This leads to the formation of tumor emboli, which have the ability to spread throughout the body (Dawood and Valero, 2012, Kleer et al., 2000). IBC tumors are diagnosed as T4d tumors, but in about 1/3 of cases are found after the tumor has formed distant metastases (Kleer et al., 2000, Fouad et al., 2017).

The need for accurate diagnosis of IBC becomes increasingly important when considering how the cancer can become metastatic within 6 months of diagnosing the initial symptoms (Woodward & Cristofanilli, 2009). The risk for misdiagnosis of IBC is unusually high and increased by many factors. One factor being that the clinical and pathological symptoms does not exist uniformly in all cases of IBC (Dawood et al., 2011). Some IBC patients present with both breast inflammation and dermal lymphatic invasion, while other IBC patients may only have one of these symptoms. Another complicating factor is that IBC is not diagnosed by analysis of histopathology characteristics, but instead is based on the discovery of the previously mentioned combination of clinical symptoms (Dawood et al., 2011).

The current consensus in the field is that IBC is not only phenotypically different, but also molecularly different from other forms of breast cancer (Radunsky and van Golen, 2005, Van Laere et al., 2013, Joglekar and Van Golen, 2012). The study conducted between multiple research groups in the International Inflammatory Breast Cancer Consortium has found a 75 gene signature profile that is closely associated with IBC (Van Laere et al., 2013). Therefore, both physicians and pathologists must think of IBC separately from other forms of breast cancer.

Until the late 1990s patients diagnosed with IBC were being treated similarly to Locally Advanced Breast Cancer (LABC) patients. It became clear that surgery and radiation treatment had little effect on the progression of IBC (Chang et al., 1998). The discovery that lymphatic invasion and distinct metastasis occur during initial presentation led to the thinking of IBC as a systemic disease, and not a locally advanced cancer.