Classification in anatomic pathology

Classification is the activity that allows pathologists to arrange the bewildering morphologic manifestations of disease into comprehensible order Ideally, our precise diagnoses would each be based on some timeless biological law of nature, and these diagnoses would group together patients with identical clinical manifestations and responses to therapy. However, in spite of the amazing success of pathology classification, it is apparent to everyone that diagnostic disagreements are common, and that patients who exactly fit into a diagnostic category often have markedly different disease courses and responses to therapy. At this time, it is unclear how quickly the potential of genomic medicine will be translated into revolutionary changes in pathology classification. However, it is clear that the rules of classification are part of the foundation of diagnostic pathology and that there is a high likelihood that pathology classification will undergo substantial changes in the next few years. This article reviews the topic of classification for pathologists who will practice during these interesting times.