RESUMEN
Breast cancer is the first cancer in women. Lymphatic involvement in breast cancer is common, especially in our patients because of the frequency of locally advanced forms. This contrast with a weak rate of diagnosed internal mammary chain invasion. To clarify the atypical presentations of internal mammary chain involvement in breast cancer. We present observations of patients presenting atypical forms of internal mammary chain involvement. The invasion of internal mammary chain is often underestimated. Indeed, this site of lymphatic spread is not accessible to the clinical exam and its radiological exploration is not systematic. Otherwise, different clinical, pathological and radiological presentations have to attract our attention to a potential internal mammary chain invasion. Our misrecognition of this site of spread and its different presentations can partly explain the lack of diagnosis