Metastasis is a process by which cancer cells leave the (initial) primary tumor, spread, and form secondary tumors at anatomically distant sites in the bloodstream or lymphatic system. is a serious clinical problem because it is a disseminated disease, often impossible to eradicate, which causes the death of most patients. Metastasis is the result of a complex molecular cascade comprising many steps, all of which are interconnected through a series of adhesive interactions and invasive processes, as well as responses to chemo-tactical stimuli. Despite its clinical significance, it remains incompletely understood. In this work we present the distribution of the different pathological sites of metastases and their origins collected at the level of the pathology department in the university medical center of Sidid Bel Abbes, Algeria and giving a general view on the phynotypic, genetotypic and histological change of the tumor. primitive after its migration and the localization of another anatomical focus by an immunohistochemical study. This is a comparative study between the initial tumor and its metastasis