KLEMPERER, PAUL (1887–1964), U.S. pathologist. Born in Vienna, Klemperer studied law but transferred to medicine. In 1923 he went to the New York Postgraduate School of Medicine and three years later was appointed pathologist to New York's Mount Sinai Hospital. Klemperer's careful research into microscopic patterns led to the understanding of several diseases. His research was in lymphomas and the structure of the spleen. With co-workers, he described the pathology of malignant nephrosclerosis and a variety of newly recognized diseases of blood vessels, alimentary tract, and the hematopoietic system. The culmination of his research was the recognition of the significance of altered intermediate substances in systemic connective tissue disease.