Differential Diagnosis for 45F with High Fevers, Rigors, Myalgia, and Swab Negative
- Single Most Likely Diagnosis
- Influenza: Despite the swab being negative, influenza can sometimes yield false-negative results, especially if the swab is not taken at the right time or if the virus load is low. The symptoms of high fevers, rigors, and myalgia are classic for influenza.
- Other Likely Diagnoses
- Viral pharyngitis: Other viruses can cause similar symptoms, and a negative swab does not rule out all viral infections. The presentation could be consistent with a viral upper respiratory tract infection.
- Bacterial sepsis: Although less likely without a clear source of infection, bacterial sepsis can present with high fevers, rigors, and myalgia. The swab negativity might not directly relate to the blood or other potential sources of infection.
- Pneumonia: Community-acquired pneumonia can present with these symptoms, and a negative swab does not exclude this diagnosis, especially if the pneumonia is caused by an atypical bacterium or a virus.
- Do Not Miss Diagnoses
- Meningitis: Although the symptoms provided do not directly suggest meningitis, it is a condition that can present with fever and myalgia in its early stages. Missing this diagnosis could be catastrophic.
- Sepsis from a specific source (e.g., urinary tract infection, diverticulitis): These conditions require prompt identification and treatment to prevent severe outcomes.
- Endocarditis: In patients with pre-existing heart conditions, endocarditis can present with non-specific symptoms such as fever and myalgia. It is crucial not to miss this diagnosis due to its high morbidity and mortality.
- Rare Diagnoses
- Brucellosis: This zoonotic infection can cause fever, myalgia, and other non-specific symptoms. It is rare but should be considered in individuals with exposure to animals or their products.
- Lymphoma: Certain types of lymphoma can present with systemic symptoms like fever and myalgia. While rare, this diagnosis should be considered in the differential, especially if other explanations are ruled out.
- Autoimmune disorders (e.g., adult-onset Still's disease): These conditions can present with high fevers, rigors, and myalgia, among other symptoms. They are rare but important to consider in the differential diagnosis.