Banti, Guido (1852–1925), Italian physician. Banti was one of the most eminent Italian pathologists of the early 20th century. In addition, he was a capable clinician, histologist, and bacteriologist. As an anatomist he added to the knowledge of aphasia, and as a bacteriologist studied the pathogenesis of infectious diseases caused by bacteria. His most important medical contributions were in the study of the pathology of the spleen and of leukemia. In 1894 he described the spleen disorder that is now known as Banti's disease or Banti's syndrome. In 1913 he composed a basic definition of leukemia that still stands.