Molecular biology, in particular post-genomics, is determining the proximal and the distal future of both biomedical research and clinical practice. Thanks to the advancements in understanding the molecular bases of diseases, we are drastically changing our approach to prevention, diagnosis and therapy. In particular, through recently available sequencing techniques, we have realised that each instance of cancer affecting a particular individual is actually composed of a set of different cancer subpopulations. This phenomenon, called tumour heterogeneity, is posing a tremendous challenge to biomedicine but also to philosophy. In this paper the notion of patchwork narrative is introduced in order to offer a philosophical framework for the description and the explanation of the many different events and processes ascribable to tumour heterogeneity and to its complexity.