[Metastasis to unusual sites]

Metastases are responsible for the majority of deaths from solid cancers. Metastatic phenomenon, complex, is a multi-step process where interactions between cells and with the microenvironment are essential. The organ tropism, that is the propensity of a cancer to metastasize to specific organs, can be explained by several mechanisms that we have described. Apart from the usual metastases, unusual sites can appear with heterogeneous clinical presentations. We describe known to date mechanisms that can explain these unusual metastasis. A summary of these locations has been realized. A rare location should always be considered in front of any atypical symptom.