Fever of unknown origin: a survey on 133 patients.

The hospital records of one hundred and thirty-three patients with fever of unknown origin (FUO) were studied. An etiologic diagnosis had been made in 105 patients: 41 patients had an infection, 24 had a neoplasm, 17 had a connective tissue disease, and 23 had various diseases grouped under "miscellaneous." FUO was self-limiting in 25 of the remaining patients. Invasive procedures (arteriography, biopsy, laparoscopy, paparotomy) were necessary to establish a diagnosis in 67 patients, non-invasive tests (sero-immunologic, bacteriologic, conventional radiologic tests, clinical course and treatment response) were sufficient in 27 patients. In 11 patients, the cause of FUO was determined in necropsy. Thirty patients died of FUO: 6 patients with a neoplasm, 4 with a connective tissue disease, and 7 with diseases termed miscellaneous.