Fever of unknown origin was a familiar diagnostic designation during and between the two great world wars. Not unlike the nonhero of the modern nonnovel, this nondiagnosis acquired an air of respectability, having appeared on numerous hospital charts as would a recognized nosologic entity. In a way this was unavoidable. What alternative was there, indeed, to the noncommittal label, after Cabot's classic triad of typhoid, tuberculosis, and sepsis had been eliminated in the differential diagnosis.
As time went on, other diagnostic possibilities were added. Nonspecific inflammatory conditions, collagen diseases, malignant neoplasms, and a variety of bacterial, viral, fungal, and parasitic infections became widely recognized as sources of protracted fever. More recently the diagnostic range was extended by the addition of the postpericardiotomy syndrome, as well as that of delayed fever with abnormal lymphocytosis and splenomegaly which occasionally follows thoracotomy, abdominal surgery, and severe injury to the chest or abdomen.