Differential Diagnosis for Fever of Unknown Origin
Single Most Likely Diagnosis
- Infection: This is the most common cause of fever of unknown origin, with a wide range of possibilities including bacterial, viral, fungal, or parasitic infections. Justification: Infections are a common cause of fever, and many can present with non-specific symptoms, making them a likely culprit in cases of fever of unknown origin.
Other Likely Diagnoses
- Connective Tissue Disease: Conditions such as rheumatoid arthritis, lupus, or vasculitis can cause prolonged fever. Justification: These diseases often present with systemic symptoms, including fever, and can be difficult to diagnose.
- Malignancy: Certain types of cancer, such as lymphoma or leukemia, can cause fever. Justification: Malignancies can produce pyrogens, leading to fever, and may not always present with typical symptoms.
- Medication-Induced Fever: Certain medications, such as antibiotics or anticonvulsants, can cause fever as a side effect. Justification: Many medications can induce fever, and this diagnosis should be considered, especially if the patient has recently started a new medication.
Do Not Miss Diagnoses
- Endocarditis: This is a life-threatening infection of the heart valves that can present with fever and non-specific symptoms. Justification: Endocarditis has a high mortality rate if left untreated, making it a critical diagnosis to consider.
- Tuberculosis: This infection can cause fever and non-specific symptoms, and is often difficult to diagnose. Justification: Tuberculosis is a serious infection that requires prompt treatment, and its diagnosis can be challenging.
- Neutropenic Fever: This is a life-threatening condition that occurs in patients with a low white blood cell count, often due to chemotherapy or immunosuppression. Justification: Neutropenic fever requires immediate attention and treatment to prevent serious complications.
Rare Diagnoses
- Familial Mediterranean Fever: This is a rare genetic disorder that causes recurrent episodes of fever and inflammation. Justification: This diagnosis is rare, but should be considered in patients with a family history of the condition.
- Whipple's Disease: This is a rare bacterial infection that can cause fever, weight loss, and diarrhea. Justification: Whipple's disease is rare, but can be fatal if left untreated, making it an important diagnosis to consider.
- Histiocytosis: This is a rare group of diseases characterized by an overproduction of histiocytes, which can cause fever and non-specific symptoms. Justification: Histiocytosis is rare, but can be serious, and its diagnosis requires a high index of suspicion.