International audienceThe rise of precision medicine represents a challenge for pathology, which must now more closely link research and diagnostic and collaborate on new bases with other specialties. Our paper is based on the study of four French cancer centers invested in developing precision medicine. Molecular biology is particularly threatening for pathologists in settings where medical oncologists and biologists believe that the discipline is capable of presiding over if not altogether replacing morphology as the principal basis for diagnosis. However, we will show that the organizational arrangements for circulating tumor specimens and producing diagnoses, as well as the place occupied by pathologists in these arrangements, have vari...