Inflammatory Breast Carcinoma (IBC) is a rare but aggressive form of breast carcinoma. Characteristic clinical and pathological features are well documented. Pathological response to chemotherapy is currently the only identified prognostic factor. This high-grade tumor exhibits phenotypical features of an aggressive tumor: absence of hormonal receptors in 56 to 83% of cases, high proliferating index, p53 expressed in 30 to 69%, Immunohistochemistry (IHC) detection of HER2 over expression in 38 to 60%. Current work on IBC points out specific molecular mechanisms: adhesion molecules such as E-Cadherin, apomucin MUC1 and angiogenesis processes contribute to the IBC phenotype. So does a gene named WISP3. This gene has been recently cloned and sequenced. It has been shown to be lost in IBC and could control tumor growth, invasion, and angiogenesis. This paper summarizes current knowledge on IBC and describes a new basis for a molecular definition of IBC.