Infections or neoplasm as causes of prolonged fever in cancer patients.

Thirty-six consecutive patients with cancer who met the classical criteria for fever of unexplained origin (FUO) were identified. A total of 18 patients had infections including all 12 with leukemia, four of 12 with Hodgkin's disease, and two with solid tumors. Fungal infections were found in nine: histoplasmosis, three; candidiasis, three; and aspergillosis, systemic sporotrichosis, or cryptococcal meningitis, one each. Six patients had unresolved pyogenic infections and one had tuberculous pericarditis. Two others had viral etiologies. Granulocytopenia was significantly more common in the FUO patients with documented infections. Clinical or laboratory abnormalities suggesting involvement of a specific organ or organ system provided important clues indicating infections. Morphological examination of biopsy specimens, with cultures, was the best method for diagnosis. In 18 patients, 12 with lymphomas and 6 with solid tumors, only the neoplasm appeared responsible for the fever. In these patients there was a paucity of abnormalities indicating organ system involvement with infection. Regardless, physicians' diagnostic efforts should not be deterred in such patients. Repeated thorough evaluations for infection are warranted.