Those who are knowledgeable in cosmology inform us that the expansion of the universe is such that the velocity at which a distant galaxy is receding from the observer is continually increasing with time. We humbly paraphrase that as “The bigger the universe gets, the faster it gets bigger”. This is an interesting analogy for the expansion of knowledge in the field of renal tumor pathology over the past 30 to 50years. It is clear that a multitude of dedicated investigators have devoted incalculable amounts of time and effort to the pursuit of knowledge about renal epithelial neoplasms. As a consequence of the contributions of numerous investigators over many decades, the most recent World Health Organization classification of renal neoplasms includes about 50 well defined and distinctive renal tumors, as well as various miscellaneous and metastatic tumors. In addition, a number of emerging or provisional new entities are under active investigation and may be included in future classifications. In this review, we will focus on a number of these tumors, tracing as accurately as we can the origins of their discovery, relating relevant additions to the overall knowledge base surrounding them, and in some instances addressing changes in nomenclature.

Human pathology. 2019 Oct 23 [Epub ahead of print]

Gregory T MacLennan, Liang Cheng

Department of Pathology and Laboratory Medicine, Case Western Reserve University and University Hospitals Cleveland Medical Center, Cleveland, OH. Electronic address: ., Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA. Electronic address: .