Approach Considerations
In general, empiric therapy has little or no role in cases of classic fever of unknown origin (FUO).
Treatment should be directed toward the underlying cause, as needed, once a diagnosis is made.
Some studies suggest a few exceptions to this general approach, including the following:
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Cases that meet criteria for culture-negative endocarditis
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Cases in which findings or the clinical setting suggests cryptic disseminated TB (or, occasionally, other granulomatous infections)
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Cases in which temporal arteritis with vision loss is suspected
Several studies have found that prolonged undiagnosed FUO generally carries a favorable prognosis.
Because of a better understanding of the etiologies and careful diagnostic approaches, patients with FUO rarely need surgical treatment.
Specific examples of treatment
In patients with hepatic granulomas, approximately 50% of patients recover spontaneously, while the other 50% respond to corticosteroid treatment (duration of therapy ranging from a few weeks to several years).
Patients with giant cell arteritis should be treated with high doses of steroids, and intravenous steroids should be administered if the patient is very ill or has significant ocular compromise. Carefully monitor the patient, since inadequate treatment and steroid toxicities (eg, hypertension, diabetes, dyspepsia, bone loss, psychosis, cataracts) can cause significant morbidity.
In polymyalgia rheumatica, the treatment consists of amelioration of symptoms with steroid therapy and close monitoring for possible development of GCA.
When drug fever is suspected, discontinue the implicated drug. Stopping the causative drug generally leads to defervescence within 2 days.
Inpatient Treatment
No evidence supports prolonged hospitalization of patients who are clinically stable and whose workup findings are unrevealing.
Outpatient Care
Conduct close follow-up procedures and systematic reevaluation studies to prevent clinical worsening. Guide further workup studies on an outpatient basis.
Patient Transfer
The need for transfer is indicated if (1) the current facility is unable to establish a diagnosis, (2) diagnostic tests are unavailable at the existing facility, or (3) the patient deteriorates clinically such that necessary level of care or consultations is unavailable.
Consultations
Appropriate consultations are indicated based on patient history, physical examination, laboratory data, and radiologic findings. Consultations include the following:
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Infectious disease specialist
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Hematologist/oncologist
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Rheumatologist
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Pulmonologist
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Gastroenterologist
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Endocrinologist
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Interventional radiologist
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Surgeon
Long-Term Monitoring
The 5%-15% of patients whose FUO remains undiagnosed, even after extensive evaluations, usually have a benign long-term course, but close follow-up and systematic reevaluation studies are essential to avoid missing potential etiologies.
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Tender subcutaneous nodules on the anterior shin and foot in an individual with polyarteritis nodosa
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Early rash of systemic lupus erythematosis. Rashes occurring the setting of FUO may be biopsied for diagnosis.[ From eMedicine article, Subacute Cutaneous Lupus Erythematosis]
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Sweet syndrome may herald a hematologic malignancy
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Psoas abscess may cause fevers, but it may be secondary to another condition that may cause FUO, including endocarditis, gastrointestinal or urologic malignancy or infection, vertebral osteomyelitis, or occult intravenous drug use. In this case, an enteric fistula due to underlying Crohn's disease was the culprit.
